As far as I know, to be road legal a motorised bicycle must either have an engine less than .25kw in power and not exceeding 25km/h, or it must pass a M-SVA test (motorcycle single vehicle approvance) which is what kit cars/motorbikes have to pass (so it's quite feasible)
As far as I know, to be road legal a motorised bicycle must either have an engine less than .25kw in power and not exceeding 25km/h, or it must pass a M-SVA test (motorcycle single vehicle approvance) which is what kit cars/motorbikes have to pass (so it's quite feasible)
Found some details here:
http://www.dvtani.gov.uk/vehicletesting/msvafaqs.asp
but I haven't yet found the specifics of the test