I haven't used Gumtree as I've heard so many complaints from friends over the years that they repeatedly delete innocent ads and photos without explanation, no warning and no refund. And have extremely poor customer service. However, lots of people advertise there. You're right generally they provide hand relief despite the 'no sex' disclaimer.
Gumtree, seems to be on the affordable end of the massage market, from £40 1hr, £60 2hr.
Gumtree clients traditionally request hand relief for a 'tip' of £20, which seems to be the norm.
I notice a couple photos of advertisers which is interesting as previously Gumtree banned human images in the massage section.