As you have a British Passport you are entitled to get VOA (Visa On Arrival) to go to Indonesia, when you arrive at fee of US$ 10.00 is charged for a 3(three)-day stay Visit Visa (single entry) or a fee of US$ 25.00 is charged for a 30(thirty)-day stay Visit Visa (single entry).
Not everywhere
Airport Entry Point :
Jakarta- Soekarno Hatta Airport (CGK)
Denpasar,Bali - Ngurah Rai Airport (DPS)
Surabaya - Juanda Airport (SUB)
Medan - Polonia Airport (MES)
Pekanbaru - Sultan Syarif Kaim II Airport (PKU)
Padang - Tabing Airport (PDG)
Manado - Sam Ratulangi Airport (MDC)
Sea Port entry point :
Sekupang , Bantu Ampar, Nongsa, Marina Teluk Senimba in Batam
Bandar Bintan Telani Lagoi, Bandar Sri Udara Lobam in Tanjung Uban
Belawan in Medan
Sibolga in Sibolga
Yos Sudarso in Dumai
Teluk Bayur in Padang
Tanjung Priok in Jakarta
Padang Bai in Bali
Jayapura in Jayapura
from KL to I would go to lang tengah (I've been twice there, also last March). Cheaper and less crowded then Redang and perhentian islands. There are buses leaving from Putra (PWTC) Station to Kuala Terengganu at 10.30pm 11.00pm midnight for about 30ringgits one way each and manage the transfer from there to jetty->resort so no worries (I paid RM 25 / pax / 2 ways)
On way back do the same, there are quite few buses mid-day early afternoon to be back at KL in the evening, ask the man of transfer to buy the ticket for you or buy same morning like I did it. Going by bus you can dive till last day!
