I am not sure if Preloved (or similar sites) is a good idea. You may end up with a pregnant or sick bunny if you are not careful! (Other members of this site did.) I think a rescue is the best place to adopt a bunny from, as it will be vaccinated and neutered. If you don't find any suitable bunnies in the rescue near you, you can try looking at the 'Rabbits in Need' section on this site. As hurricanhoney said, rescues here rehome nationwide.