You need a 12month bank statement and probably 12 months of credit advice notes if your statement doesn't prove it comes from abroad..my husband did it last week
our "fall back" money is in offshore funds & has gone up in value more than any property & we can access it pretty quickly. The offshore bank account is just a basic account if we ever need Pounds. We didn't want the hassle of looking after a UK property whilst living here. We are lucky that this will buy us something elsewhere if necessary
We no longer use a UK address of any kind. We couldn't keep asking friends to post bank cards etc. Nationwide accepted our Thai address so we keep a very small amount there & the rest is in an offshore bank account!
The only bank that will let us have an account with a Thailand address is Nationwide. Barclays closed our account and Santander as our address is in Thailand.