Never done that job butvwhen I priced up the price of chains, sprockets and tensioner a few years ago the parts alone from Island-4x4 came to £350. Probably another hundred or so by now with prices as they are.
@tomcat59alan might have done but without RAVE I'd think fan out, belts off, pulleys off, alternator and power steering pump off. Guess removing the rads at the front isn't necessary but would massively improve access. Sump will have to be dropped down. Wammers said you didn't have to take the head off and you could get the front cover out by dropping it down a bit. Then it is just the sprockets, chains etc. That crank bolt is 'kin tight but with a windy-gun you'd be OK. Book time probably 2 hours but reckon you'd do it in 4 hours for certain? So depending what parts and what quality they are I'd think you're looking at a minimum of £600 and more likely £800?
@brianp38dse might have done it, or done it on a bimmer.