I wouldn't have thought that anything being shipped to a UK, US Air Force base would have anyproblems - as long as it's being shipped from an air force base in the states.
You gotta be careful, cos if it's regular mail from the states going to an Airforce base in the UK you can bet your mama that the security is going to be like Fort Knox and they'll open every outsider package - but if, on the other hand it's being shipped from a fellow air force base in the states to a base in the UK and flown by the US Forces mail then I'm sure it'll get through. Especially if it's labelled as a gift for someone on the uk base. If they don't open it, they definitely won't tax it and they can just hand it off to you once it arrives.
Now all ya gotta do is get someone in the forces in the states to mail it via US Forces mail to a bloke in the forces over here! Piece o' cake!!
I know that there are a couple of guys on the forums who are US Military blokes stationed over here (in the UK). It might be worth checking with them - I can't remember who they are though. Good Luck