If you cannot call 1-800-My-APPLE from UK, then I am not sure how this would be handled. These are the only options: http://www.apple.com/contact/
As for your side note, Apple would probably love to hear your feedback. They also have a contract with FedEx. If UPS causes enough of a problem, they could easily choose to use FedEx for international shipments—they just need to know about the problem: www.apple.com/feedback
Also, have you tried going to the US store at apple.com (option in bottom right)? If you do this, you could log in, and choose the pre-sign option (account>view order history>login or enter order number). This would allow UPS to drop it off without signing. This way if your Uncle is stuck at home anyway, then all he needs to do is check the front door a few times a day.
Hope it gets worked out!
I didn't know about the pre-sign package til the day after the shipped the package back to Apple and now my card is charged and my aunt still has nothing and I still can't find a contact number that isn't a 1-800 I am getting soooo frustrated.
Altho your info was very helpful I still haven't been able to get in contact with apple
If the "Chat" option doesn't appear on the Apple Store page, and it seems to be unavailable as of now, you will have to find a way to call a US 800 number from the UK, since the US Apple Store has no published e-mail nor international numbers. If you search the web for "call us 800 number outside us", you'll find a number of ways to do this, including using Skype.
You could try two things, get in contact with apple in the UK
find a proxy server that will display you IP as being in the US and see if that will bring up the live chat option.
Hope this helps.