I'd buy an Italian card in an Italian shop, but that ebay shop is a Wind dealer so I think you can trust it. BTW I don't see the problems for refilling since you'll be using the Wind card in Italy and you can find top-ups almost anywhere in my country!
You can also refill Wind with O2 scratch cards when you are back to UK, if you wish to keep the card active.
I'd go with Orange for F and CH and Wind in Italy.
Where exactly are you going? Maybe we can tell you if you have 3 coverage, which is surely faster than Wind (3G, often HSDPA, while Wind will probably be just GPRS, maybe EDGE).
BTW refill problems outside of Italy will be normal with all 4 Italian operators. I think with Wind you have more chances to get it refilled also in Britain.