Import models only have 2yrs Warranty, not 3, the 3rd year is provided by VW UK, which if imported, it wont have. Unless they offer you some kind of warranty with the car of course, but the standard 3yr thing wont be applicable.
My experience on this kinda thing is that imported cars tend to be of higher spec as the cost of the car is usually lower, so you get more for your money and if you're planning on having the car for a while then resale value shouldnt really be such an issue, esp as when cars depreciate this gap that seems to appear between import and Uk cars will narrow.
Personally, once a car is outside of warranty, as long as the car is UK spec i dont see what the issue is with UK car or Import car with UK spec yet people dont seem to want to pay the same money for them - makes no sense to me at all.