I will be in London beg. of April. I have booked train tickets to Birmingham with Virgin Trains. Now I'm wondering if I'll be able to collect my tickets from the FastTicket machines at Euston station with my American credit card (with which I booked the tickets). Does anybody know? If I can't use the machines, is there a Virgin Trains counter at the station where I can collect the tickets?
Thanks!

I've done it a couple times (not from Euston, but from King's Cross and from Fenchurch St.) and it works fine.

And I've done it at Euston (to Bletchley).

Thanks for the replies! I guess I can relax now, even though I still feel a little jittery about using an American credit card in Europe.

I can't speak for the rest of Europe, but don't worry about Britain, even with the pin & chip thing, pretty much everyone who takes credit cards will take American ones (provided it's Visa or Mastercard, of course).