I was in the same position, as yourself only two months ago, as im an Rc plane flyer, and the winds were too strong to fly, So i refurbished my late Grandfathers boat, to a sea fairing, ok, pond muddling Rc boat
i found a local club, (Millpond Crawley Sussex, UK) and with there website, knew what days they meet,
I met up with said members, and with a freebie, sailed my launch with their permission, and joined the club two days later
Now for me, as an RC flyer (and a bad one at that) i am fully aware, that insurance is paramount, and randomly sailing a boat, or whatever, without insurance, is not a very wise thing to do !
For the sake of a £20 fee, with insurance, its a no brainer