Reply to UK Buyer from DJTT, procedure if there is an issue?

I am looking to buy an S2 from the DJTT store, and get it shipped to the UK.

However, if I come across a problem or a fault with the Hardware, how would I go about getting it sorted? Would I have to pay large amounts to get it shipped back to the US?

I am sure it will be fine, but just looking at any issues that may occur, as apart from some chroma caps, I have never bought from the US before. Economy delivery, what is the average time to UK also?

(If this is in the wrong place feel free to move or delete)