You will need the AM category on your driving licence, this covers light quadricycles (weighing under 350kg with a top speed of 45km/h - about 28mph). To get one you need to be over 16, have a provisional licence and pass the CBT, a theory test and a practical test.

There aren't many Aixam or Microcars for sale, however. We've spotted a few on Autotrader but eBay is your best bet.