Thanks to everyone for your replies. They've been helpful.
This probably belongs in the "deposit & withdrawal methods" subforum, but I checked out their deposit and withdrawal methods. If I deposit by non-UK credit card then I have to cash out by either check or bank wire--and all such transactions are done in pounds sterling. My bank takes 30 business days to clear a check in US funds, let alone one in pounds. I'll be cashing out from them only as a last resort.
Incidentally, I never got an acknowledgement email when I registered my account and can't find any place on their website or in my poker client to verify my personal information to make sure I entered the email address correctly. I emailed their support people about that and haven't received even an acknowledgement yet. ... Which is at least better than Full Tilt, which takes TWELVE DAYS to reply to a support email.