Hourly rates for corgi reg plumbers in uk?

As the title suggests,we are trying to find a plumber in the Sleaford area of lincolnshire to give us a fair price to fit a new gas combi boiler as the old electric floor boiler has died!The pipework is already there as there was a gas boiler in there 17 years ago.So far the 2 quotes we have had seem rather high as we can get the boiler at trade price so just need the plumber to put it in.