Not specifically age-verification, but they are considering checks of some sort at some point to deal with the bot problem on there. That’s at least one angle. They’ve also just rolled it out in small scale to suspicious accounts. So whether or not it is done for the purposes of verifying age, or just dealing with bots - I suspect it’ll arrive in the end once they feel they have the capital to do it.

As for the UK specific issues, it’s hard to get a concrete numbers because most people in the UK just switched to a VPN. In the event of Reddit implementing global ID-check measures, it wouldn’t matter what VPN you switched to.