I couldn't find a lemmy community for your party after having a search around, so figured why not make one!
First time making a lemmy community, so let me know about any issues.
Is it important?
Given that's a British party and the participants will be mostly British and connecting from Britain, then yes.
Surely this is the strength of federation
I'm not sure what you think is a strength here. Just because you can create a community anywhere doesn't mean it's a good idea to ignore geography or jurisdiction.