Perhaps you could do a Google search for UK user groups whose topic are related to politics or government. I belong to one whose members are fans of British movies.

I think you will find it is very similar to politics in the US – there are some jurisdictions where there is a vibrant democratic process, and others where there is cronyism and other shenanigans taking place.

If you find information, please re-post it to this question, because it’s a good question and I wouldn’t mind learning more myself.

Probably the best way is to get involved, at least for a few years. Find a candidate who represents some (or all) of your viewpoints, and volunteer to work on that person’s campaign.