I would be worried with a job for £1800 it does not mean £5k will be good I did my respray three weeks ago but on the continent due to prices for decent shops, my good old friend did it for me - old league repray done by guys in their 50s hehe - full attantion to detail, spray cabin , STANDOX german paint used, full respray with windows out, all cavities done at the same time, clear coat applied twice for extra deep gloss on black colour - £2.5k it took him two and a half weeks.
Very pleased with the job.
I would say definitely do your research as it might end up as a total disaster, all body shops give 6 months warranty on paint but even totally fucked paint will look good for 6 months, this is my second repray in 3 years as first job was bad after 2 years paint started to look crap.