I redirected any traffic going to the error not found pages to my homepage instead. That seems to have sorted it.
I purchased a script for $15 to minify the HTML and CSS - this added 2 points to my pagespeed rating.
I used .htaccesss file from
http://html5boilerplate.com/ which has sorted out my cache validator for 8/12 things. not sure how to fix the last 4

They are image files - png and jpg in catalog/theme and images/cache respectively. (images because I have a subdomain for image files)
My htaccess now looks like this: (- dont laugh, I am a complete newbie, without any programming experience, so if it looks poor, let me know what I am doing wrong, and help me correct it please, instead of just mocking my inexperience?! ha!! ha!!)
# 1.To use URL Alias you need to be running apache with mod_rewrite enabled.
# 2. In your opencart directory rename htaccess.txt to .htaccess.
# For any support issues please visit:
http://www.opencart.com
# Options All and FollowSymLinks are disabled on this server.
# FollowSymLinks is automatically replaced to SymLinksIfOwnerMatch, All is changed heuristically.
Options +SymLinksIfOwnerMatch
# Prevent Directoy listing
Options -Indexes
# ----------------------------------------------------------------------
# Expires headers (for better cache control)
# ----------------------------------------------------------------------
# These are pretty far-future expires headers.
# They assume you control versioning with cachebusting query params like
# <script src="application.js?20100608">
# Additionally, consider that outdated proxies may miscache
#
http://www.stevesouders.com/blog/2008/0 ... erystring/
# If you don't use filenames to version, lower the CSS and JS to something like
# "access plus 1 week" or so.
<IfModule mod_expires.c>
ExpiresActive on
# Perhaps better to whitelist expires rules? Perhaps.
ExpiresDefault "access plus 1 month"
# cache.appcache needs re-requests in FF 3.6 (thanks Remy ~Introducing HTML5)
ExpiresByType text/cache-manifest "access plus 0 seconds"
# Your document html
ExpiresByType text/html "access plus 0 seconds"
# Data
ExpiresByType text/xml "access plus 0 seconds"
ExpiresByType application/xml "access plus 0 seconds"
ExpiresByType application/json "access plus 0 seconds"
# Feed
ExpiresByType application/rss+xml "access plus 1 hour"
ExpiresByType application/atom+xml "access plus 1 hour"
# Favicon (cannot be renamed)
ExpiresByType images/x-icon "access plus 1 week"
# Media: images, video, audio
ExpiresByType images/gif "access plus 1 month"
ExpiresByType images/png "access plus 1 month"
ExpiresByType images/jpg "access plus 1 month"
ExpiresByType images/jpeg "access plus 1 month"
ExpiresByType video/ogg "access plus 1 month"
ExpiresByType audio/ogg "access plus 1 month"
ExpiresByType video/mp4 "access plus 1 month"
ExpiresByType video/webm "access plus 1 month"
# HTC files (css3pie)
ExpiresByType text/x-component "access plus 1 month"
# Webfonts
ExpiresByType font/truetype "access plus 1 month"
ExpiresByType font/opentype "access plus 1 month"
ExpiresByType application/x-font-woff "access plus 1 month"
ExpiresByType image/svg+xml "access plus 1 month"
ExpiresByType application/vnd.ms-fontobject "access plus 1 month"
# CSS and JavaScript
ExpiresByType text/css "access plus 1 year"
ExpiresByType application/javascript "access plus 1 year"
<IfModule mod_headers.c>
Header append Cache-Control "public"
</IfModule>
</IfModule>
# ----------------------------------------------------------------------
# ETag removal
# ----------------------------------------------------------------------
# FileETag None is not enough for every server.
<IfModule mod_headers.c>
Header unset ETag
</IfModule>
# Since we're sending far-future expires, we don't need ETags for
# static content.
# developer.yahoo.com/performance/rules.html#etags
FileETag None
<IfModule mod_deflate.c>
<FilesMatch "\.(js|css)$">
SetOutputFilter DEFLATE
</FilesMatch>
</IfModule>
# compress the files
AddOutputFilterByType DEFLATE text/html text/plain text/xml text/css text/javascript application/x-javascript
# removes some bugs
BrowserMatch ^Mozilla/4 gzip-only-text/html
BrowserMatch ^Mozilla/4.0[678] no-gzip
BrowserMatch bMSIE !no-gzip !gzip-only-text/html
Header append Vary User-Agent
# compress text, html, javascript, css, xml:
AddOutputFilterByType DEFLATE text/plain
AddOutputFilterByType DEFLATE text/html
AddOutputFilterByType DEFLATE text/xml
AddOutputFilterByType DEFLATE text/css
AddOutputFilterByType DEFLATE application/xml
AddOutputFilterByType DEFLATE application/xhtml+xml
AddOutputFilterByType DEFLATE application/rss+xml
AddOutputFilterByType DEFLATE application/javascript
AddOutputFilterByType DEFLATE application/x-javascript
# Prevent Direct Access to files
<FilesMatch "\.(tpl|ini|log)">
Order deny,allow
Deny from all
</FilesMatch>
# SEO URL Settings
RewriteEngine On
# If your opencart installation does not run on the main web folder make sure you folder it does run in ie. / becomes /shop/
RewriteBase /
RewriteRule ^sitemap.xml$ index.php?route=feed/google_sitemap [L]
RewriteRule ^googlebase.xml$ index.php?route=feed/google_base [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_URI} !.*\.(ico|gif|jpg|jpeg|png|js|css)
RewriteRule ^([^?]*) index.php?_route_=$1 [L,QSA]
# Prevent Directoy listing
Options -Indexes
### If you get an "Internal Server Error 500" after enabling any of the following settings, restore the # as this means your host doesn't allow that.
# 1. If your cart only allows you to add one item at a time, it is possible register_globals is on. This may work to disable it:
# php_flag register_globals off
# 2. If your cart has magic quotes enabled, This may work to disable it:
# php_flag magic_quotes_gpc Off
# 3. Set max upload file size. Most hosts will limit this and not allow it to be overridden but you can try
# php_value upload_max_filesize 999M
# 4. set max post size. uncomment this line if you have a lot of product options or are getting errors where forms are not saving all fields
# php_value post_max_size 999M
# 5. set max time script can take. uncomment this line if you have a lot of product options or are getting errors where forms are not saving all fields
# php_value max_execution_time 200
# 6. set max time for input to be recieved.
# Uncomment this line if you have a lot of product options or are getting errors where forms are not saving all fields
# php_value max_input_time 200
# 7. disable open_basedir limitations
# php_admin_value open_basedir none
Things I have got nowhere with yet....
Defer parsing of JavaScript - I dont have a clue where to start with this
I understand that I need to move the js stuff to the bottom of the page.. but which file???
I have installed cloudflare cdn, but my dns has not updated yet, so I can't give any feedback.
It would be great if someone with far more knowledge than me had written a guide on 'optimising Opencart for Google Pagespeed'
Anybody know of such a thing? I seem to have been searching most of the night
