i did my 125 a few years back , didnt even need a brake light then !! only needed a horn. it was put on Q plate , it does take a while to get all the relevant paperwork sorted with the dvla though.
if i can give you one piece of advice with it , dont do as i did and polish off the "not for road use" on the tyres because although its great fun sliding the arse around on knobleys it isnt fun when you have to brake hard it hurts ! a lot !!