The Gambian dalasi is available in UK banks, but the exchange rate is better if you wait until you are in the country. Take Pounds sterling, don't change in UK.

It may be a good idea to get a small amount of money bfore you leave for arrival expenses, then make exchanges for more once you've arrived. There are small bureux de change in all towns and it's very easy to change sterling Euros and dollars anywhere. You'll also find that although Visa credit cards can be used to get cash from Gambian ATM's you are very limited in using Visa generally. There are just a few places that accept payment with Visa and only in the major tourist area, no one in the 'real country' accepts any credit card. Other cards like Master are no use here at all.

Recently, the exchange rate at Gatwick was 37 Dalasi to the pound, in the Gambia it was 47! Every where wants cash & the hotels often charge 5% if you pay with credit card; engish is accepted at 42 to the pound.