It's a bit tricky. I'm no expert by any means, but I know that an ordinary assisted electric bike which does away with the need for pedalling and doesn't go very fast is quite legal. However some forms of powered transport are not legal for use on anything other than private land, like segways (shame, cos I'd love one!) , motorized foot scooters, and I know the speed can make a difference. That is actually going to be the biggest hurdle - whether something is legal to use on the road or not. Maybe checking out the DVLA website might help.