I have another question about working. I've read some things about an NI or so. Do you need one of these to start working? I was thinking it might be fun (if not impossible?) to head to the cities i'm interested in and see if I couldn't sign up with a temp agency and do some temp work, just to see what the city is like and not to just spend the time as a tourist.
An NI (National Insurance) number is required to make sure that you are taxed at the correct rate and your National Insurance contributions are correct each month (it's a little bit like a SSN, but is just for working/contributing to NI).
UK residents are automatically assigned an NI number when they turn 16 (and can legally work full-time), but if you have just moved to the UK, you will need to apply for one yourself.
It is possible to start working before you have applied for your NI number, but you will most likely be taxed at a higher rate than you should be, so you will have to get a tax refund once you have your number and your tax code is adjusted.
A lot of companies now ask for your NI number when you are filling out your contract details, so it's probably a good idea to just apply for one as soon as you move to the UK, so that you have it ready for starting work (you just have to show that you are looking for work).
You can find out how to apply for one here (it's done through the Job Centre in the UK):
http://www.hmrc.gov.uk/ni/intro/number.htm