Hi, the city literary institute does do weekly courses which may be cheaper. You can look at their courses online: http://www.citylit.ac.uk/
Otherwise my tutor at drama school was Jonathan Leverett and he was brilliant and so patient – a really good teacher. He teaches at BASSC: http://www.bassc.org/aboutFrameset.htm
Check out their website and if you need some advice on the right course for you, email him at BASSC: jonathanleverett@bassc.org
Good Luck!
Nadia