Java #34 & Concerto #35, I was able to sign up on TCB--UK just fine with my USA address ! It even had a scroll-down menu for me to pick my State once I answered USA for my country! Only think is, the UK version of hotels.com rejects me with a warning that I must enter my UK bank account details to get cashback--but their Irish option has no such restriction !
The Irish version of hotels.com includes all taxes & fees upfront--and on hotels on the Caribbean island of Grenada, the euros price is 5% cheaper than the dollars price after conversion! As in 100 euros which = US$106.50 today per xe.com vs. US$112. And I use a Visa & an Amex without forex commissions.
I have entered my PayPal email & my BA Avios number. I expect it to ask me each time into which one I want paid.