I can't recommend British Gas highly enough. I've got Homecare400 covering central heating, electricity, plumbing and drains. You can make appointments on line for when you want. The workmen always take their time and do a proper job because they are not in a rush to get to a more lucrative job as an independent trader might be. I trust their qualifications to do the job and have never been disappointed yet.
My daughter has just bought a house and signed up to the same Homecare400 a month ago. In the last month she has had an electrician to sort out a lighting problem, the boiler man is coming next week to give the boiler an annual service and last week her front drain overflowed and a chap came and cleared the problem. He continued to jet the pipes until he was happy with the flow, a cowboy would have cleared the blockage and left.
For £29 a month for the first year, I think my daughter has had her money's worth already. I pay about £39 a month. We are both women without partners so it is marvellous to be able to call someone who will do the job and not rip you off.