but scooter type might be good if you want to get your bike legaly registered as a motorbike.
under uk law your vehicle has to meet cirtian safety standards which they do test for. these include headlights, indicators, mirrors, horn, brake lights etc. a scooter type bike would be a better starting point if you wanted to be a leagal motor bike because it has most of these things already. scooter style also has more streamlineing fairing stuff so therefore it will go faster.