The UK credit Card or a Debit Card is no problem whatsoever.
I live in Spain am at present the Malaysia, last week I was in Thailand and the month before that in Philippines. I used my card everywhere exactly as one would in UK.
You are of course charged in the local currency, and if you are lucky enough to have a card with Nationwide, you get the best exchange rate and only a 2% charge (plus £1 per transaction if you draw cash, but take care to choose an ATM which does not charge).
As for IKEA. I have never bought anything from them