Having only done DIY for decades, a few years ago I got PL&PI insurance to be able to sort out the electrics at church. My last renewal was ÂŁ225 inc extra taxes etc. That's to cover electrical work (not restricted in type of property), T&I (invokes the risk of PI liability), and "general handyman" which I got added for no extra. IIRC it could have been somewhat cheaper without T&I, or with electrical work restricted to specific premises (either domestic or domestic and commercial).
Had an interesting exchange with them as the policy excludes all work in or on towers and steeples - which excludes a lot of our church, including most of the electrics. Eventually they confirmed, after I insisted they send my query unaltered to the underwriters, that I was covered as long as I wasn't working "on" the tower. I'd pointed out that risk wise it was little different to working in a domestic house.
But prior to that, I had had discussions with one of their sales guys, who basically said the premium is generally based on the riskiest trade being insured. Plumbing is one of those risky trades and would have doubled the premium - not that I have a great desire to get into that anyway ?