Change delivery times depending on stock location.

HI,
One of our suppliers sends us a spreadsheet that contains the product details.

One of the fields is 'In Stock' showing that they hold stock of that product.

We have a shop that holds a certain amount of stock.

Lets use part numbers 12345, 12346, 12347 as an example

If we have 10 X 12345 we can show on the system our stock levels. Available for next day delivery or collection.
If we do not have stock of 12346 and our supplier does we need to show ('2-3 days delivery / at central warehouse') but still show for sale.

If our supplier is out of stock show 'On back order 3-4 weeks'.

Any help appreciated.

SteveW