Difference between a US and UK Office 2010 Pro

I need 20+ copies of Office 2010 Pro, as they are no longer for sale, I have been trying on ebay, but so far the 4 copies I purchased all turn out to be fake, even though the seller assured me it is genuine and the price of around £140-£160 seem fair for an older product.
So I am now looking to other countries for this, the only two countries that may be able to fill this gap is Germany and the US, the US seem to have better pricing and their description seem more genuine than the German ones, I am just wondering if we could buy the US versions and use them in the UK ?

To answer your question as to why not 2013, simple answer is the server is 2003, so Outlook 2013 won't work with it correctly, 2010 seem to be the last version that could support server 2003 totally.

Would be most grateful for any help on this as I need to do this pretty soon.

Thanks