I always use them and never been let down by the works.I would strongly advise against this route at all costs.
the most common distress thread posted on this forum is people being ripped off or failed by inept tradesmen and they always lead back to these sites.
try Joining your local Facebook group and asking on there.
if you have a local independent plumbing merchant gomand ask them for some leads.
And, if you see any extensions being built by a building firm in the streets near you - pop your head and ask to speak to the builder running the job or one of their tradesmen - these guys have contact details of good tradesmen in their phones.
Many really good tradesmen don’t advertise because they have too much work - and builders build their contacts via networking: either through seeing guys on site or in the pub.