Last few times there I used my credit card and US dollars. Some outlets do accept other currency but exchange rate will not be in yr favour. Lovely airport. Enjoy.
Just take your debit card and put it in the hole in the wall in Dubai to take out as much local currency as you'll need for your stopover. We never buy local currency in advance, I won't carry large amounts of cash.
They`ll probably take pounds or US dollars in small outlets. If you use your credit card in the duty free they will ask you if you want to be billed in local currency or sterling. Don`t opt for sterling. They will rip you off on the exchange rate. It`s better to pay on your credit card and let your card company sort out the exchange rate.
as boxtops said - do a quick spin of the duty free, shops and restaurants and estimate how much you need and then draw cash on the debit.
Keep the slip......a mate of mine was copied in HK airport and only got reimbursed by being the Finance Director of a major project out there....salutory lesson for keeping slips.