Weapon restrictions for lightweights?

Now I may be missing something obvious here, but I've had a look around and couldn't see anything that stood out.

For live events in the UK, what weapon restrictions are in place at the moment? For Extreme Robots, RoboChallenge and Robots Live if you know for all three. Quite frankly I'm struggling to even find entry pages or rule documents for all three of the organisers!

Just wanting to know because I have a design for a featherweight spinner that I've been refining for quite a few years now, and I'm finally in a position to actually build it but I really don't want to go through the expense of doing so if there are bugger all events where I'd actually be able to fight with it.

Extreme Robots are about to bring out their new spinner-proof arena in April I believe, so that's one. And then there's the Robochallenge featherweight championships, which seem to be once yearly. Though this year's hasn't been announced yet, if it is going to happen.

If it's a featherweight spinner you will be able to run it in the robochallenge arena. It's a grade 2F arena which essentially means it can run any spinner in that weight category.