Dear Sir,
I can implement your projeckt in the following mode:
1. - I will add a new taxonomy term to the Product content type, we can name it Stock, with walues "UK stock" and "Overseas Stock".
2 - After this with views we will make the "In Rush" page for the products in the UK - filter with "UK stock" taxonomy term.
3- with "Better Exposed Filter" module we will make a search box, where the user can search for products (1) typing the keyword and (2) selecting the delivery options: "in a rush" or "standard delivery".
At the end Of course we will ad the social buttons to products page.
I think this is a simple and great solution for your problem.
Observation 1: in the drupal commerce the SKU is always uniqe. But we can add another fields, with name "UK SKU", "FR SKU", "USA SKU" - or what you want.
Observation 2: mybe you must upgrade your site to Drupal 7. This is a longest process, because you cant upgrade directly to the 7 version, first must upgrade to drupal 6 - but only on a test server!.
Dear Sir,
I have registrated myself just for a short time, this is the reason why I do not have recomandations. In my portfolio page you will find a short reference of my works.
I am looking forward for your replay.
PS: are you sure your site is Drupal 5? I think is Drupal 7 ....
Thank you,
Lehel Lazar