just to remind you that you'd better think well before moving abroad on your own. Thailand is a nice country and people are friendly, but it may be a little difficult for a single foreigner to settle without proper preparation. you'd better have some host or trustworthy friends in case you need some help. most Thais are honest, but not all.
about the accommodation, it depends on how long you'd stay. if it is for a short trip (probably for weeks), i'd recommend the guesthouse around Khao San area. The room with air-con should cost you around THB 500 +/- per day. (GBP 11 +/-)
If you want to go for long-term (4 months or more), there are many places for you to choose. The rent depends from the area. I'd say the cost of budgeted room with air-con in a fair location would cost about THB 5,000 - THB 6,000 (GBP 110 - GBP 128). However, the electricity and utilities will be extra, but should cost no more than THB 3,000 (GBP 65) if you are not a heavy user. anyway, you may need someone to help you with the rental contract. 2 - 3 months rental deposit is also required for this kind of rental. There are also many great places to stay if you have generous budget.
Noted that I use the exchange rate of THB 47 per GBP 1 in conversion. The actual exchange rate can be varied.
about the book, there are many great stores around Siam area. you may try "Asia book" and "CU book center". for DVD, it'd be a little difficult to find the shop that offer pre-order. i'd recommend to go online. anyway, there are many places you can get "cheap" DVD. if you really move here, i can give you more details about the places.
