The rate with the post office is 47.9126 and the money is commission free. You have to get at least £350 worth though. Is it worth getting some? What is the rate in Thailand if it only saves a couple of quid its not worth it. How can you find the exchage offered in Thailand at the minute?
I would wait until you get to Thailand. Firstly the sterling is creeping up against the Baht so if you wait it might improve even more; it's almost 52 to the £ at the moment. Secondly, £350 is a lot to be carrying around with you. If you use your UK atm card to draw money out of your bank once you are over there you won't have to carry so much around, and the fact that you get charged by your bank will probably be offset by the fact that the bank will get you a better rate.
Not sure how you can find out about the exchange rate in Thailand.
[ Edit: Edited on 06-Feb-2009, at 13:10 by bex76 ]
I would very strongly advise against getting money from the post office.
They say it's commission free, and technically this is true, but the rate is a complete rip-off. The official rate today was roughly 51 Baht, so if you change money in Thailand they give you it at about 50.5 Baht. The travel agents and post office in England all mislead people with their 'commission free' claims, which are technically true, but i could give you an exchange rate of 1 Baht to the pound with no commission but this would still be a rip-off.
If you have a Nationwide flexaccount you can use the ATMS here without getting charged and you get the official rate, i.e. 51 Baht today. Even if you haven't got a flexaccount you could bring cash with you and get a much better deal from Thai banks than the post office is offering.
Having said that, I always like to come out here with about ten or twenty pounds worth of Baht, just so I can pay for the airport bus and my first night's hotel without having to find an ATM first (although actually there's plenty of ATMs in Bangkok, so just enough for the airport bus would be enough.
Also, once you get to Thailand if you use the ATMs here the yellow bank doesn't charge a fee, but the purple bank has started charging 20 Baht in some places. 20 Baht is only 40p but I still use the yellow bank.
Also, if you want to keep up-to-date with the official rate then go to oanda.com and click on FX converter under currency tools down the side. Make sure you use 'interbank rate' to find out the official rate. In Thailand banks generally offer you about 98-99% of the interbank rate. In England it's generally about 90%. Ten percent less than the official rate is a complete rip-off in my opinion for a transaction that only takes a few minutes.
Another way to check the official rate is just to look at the 'we buy at' rate then compare the 'we sell at' rate, then split the difference.
The only other advice I would add is that I know Barclays totally rip you off as well if you make withdraws from a Barclays account while in Thailand. The first time I came to Thailand the exchange rate was 75 baht and I got 75 Baht when I used my nationwide card, but with my Barclay card it was about 66 baht (cos they took two charges off me and gave me a rubbish rate).
I'd just like to add a thank you for the information on this thread. Really helped as i was about to ask the same sort of question.
Off to Nationwide to open an a/c then......