I’ve done a fair bit with a rope, rack and bivy gear.
Dartmoor is a good place to start as you can get away with a 25m single rope and you can link the crags up more or less legally – if that bothers you.
Northumberland is also good and the North York moors offer some good bouldering at obscure outcrops that are rarely visited.
They sort of dovetail nicely – ride bike, put a brew on, sort rack, climb route and then ride off to next crag. Repeat until it’s time to bivy. Reality strikes when for the first time ever you realise mountain biking is hard on the arms and hands. That easy severe becomes a full on arm pump and you fingers peel off, of the top out. Ouch! (Thanks very much Geordie guide book writer).
I have a kit list somewhere if you are interested?
Hth
Marko