Me and a mate of mine ride Rivington Pike quite often. We both live in Bolton, but I am away at university at the moment. If your into MUni the pikes got some good downhill sections.
There are some other people who sometimes go unicycling up there, but I cant remember who.
Theres also a unicycle club in Denton, and the Cumbria MUni club.
its all rideable on a 20" i would say, you should head up for a play around sometime, wasnt at all busy last time we went up, good place for an afternoons ride, theres also a few quarrys nearby that are good for trials
We run a weekly unicycle club over in Denton (East side of Manchester) which you're more than welcome to come along to. We meet on Tuesday evenings from 7-9pm.
Here's a link to directions recently posted when we organised a hockey tournament. There's also a map of the school grounds showing where our hall is.
I ride up and around Rivington practically every weekend. At the moment I'm up there Saturday mornings just as it gets light (for a couple of hours). You're more than welcome to come along for a ride, but I must say it's more muni than trials that I do.
I'm mainly a muni person ( i do have a nimbus 20) but I always tend to post before and after any event organised by myself. Sometimes it's quite late notice 😉
I wouldn't mind doing Rivington again sometime as I haven't gone through the Chinese gardens.