how much would it cost to re-decorate my living room?

you need to take your car to a bodyshop and get someone to take a look at it and quote you..

i paint cars for a living and it is impossible to quote on anything to do with bodywork without seeing the car!

it could cost you anywhere between £500 and £5000
depending on what you want - quality, colour, extent of repairs, prep work etc. what their overheads are what reputation they have etc. the list is endless. no two places will charge the same and no two places will give you the same quality of work!
best thing is go by word of mouth and to see what they produce for your own eyes..

asking on an internet forum is just going to open a big can of worms and get you no REAL idea of price..