Citizens of most countries (including UK and US) do not need to apply for a visa to enter Malaysia providing the trip is for tourist purposes and the length of stay no more than 90 days.
In all cases a valid passport is required with at least six months remaining beyond the date of entry. Also, all travellers must be in possession of a return or onward ticket and sufficient funds (at least �250). It is advised that you enter Malaysia on the passport on which you exited your last country of departure, as dual nationality is not recognised.
Unless flying from Malaysia (where it is already tacked onto the ticket price) you will have to pay a �20 departure tax when flying international.
Malaysian Embassy in London
Malaysian High Commission,
45 Belgrave Square,
London SW1X 8QT.
Tel: 020 7235 8033
Malaysian Embassy website