I want to add some text into the box where the product pricing is displayed on the product page.

Just want to add "RRP Inc Tax" in front of the struck out Price
And then "Our Price Inc Tax" in front of the sale Price
I have had a bit of a go, but discovered that as the price is generated differently depending on whether Special, Discounts or Options are in place, I have admitted defeat.
This is probably a fairly straight forward edit, it's just beyond me.