Robots Live are usually at the Comic Con at the NEC, they were there just a couple of weekend ago I think. Might not be back until November but those events are on a very informal level so plenty of time to meet/chat to the roboteers and ask for a look at some machines. A lot of featherweight builders have heavies too so can offer advice, and Robo Challenge also occasionally host events at the NEC for the feather championships; used to be part of the Gadget Show Live but now it would be Insomnia Gaming Festival. They won't be at the April one but there's another in August they might be at.