I was intrigued by this comment so double checked with the DVLA. I asked " Can I drive a Twizy (L7e Heavy Quardacycle) on a Provisional car license. This was the response. I have highlighted what i believe to be the relevant parts.
Thank you for your enquiry received on 17/5/2018.
Your case reference number is 00614122.
We appreciate that you have taken the time to contact us in relation to this matter.
Provisional category B licence holders can drive heavy quads, but not light quads (with a MAM of less than 350kg) as these sit within category AM, to get category AM an able bodied rider will either have to:
Pass a CBT, theory and practical test in AM or one of the other A categories
Pass a theory and practical test in category B, and then pass a CBT in order to validate the AM category
Provisional drivers of such vehicles used on the road must have the appropriate entitlement. The driver will be subject to the provisional licence conditions.
**There are exemptions from the need to be supervised, by a qualified driver when driving: **
• a motor vehicle constructed to carry only one person which is not adapted to carry more than one person and is a vehicle in sub-category B1 (invalid carriages) a motor tricycle, a motor vehicle having four wheels and an unladen weight not exceeding 550 kg or a motor vehicle included in category F, G, H or K. (Regulation 16(3) (a) of The Motor Vehicles (Driving Licences) Regulations 1999 as amended).
• a motor vehicle of a class included in former sub-category B1 which is adapted to carry only one person and has at any time between 1st August 2002 and 1st March 2003, had the use of an NHS invalid carriage that was issued to him by reason of his having a relevant disability. (Regulation 16(3)(a) of The Motor Vehicles (Driving Licences) Regulations 1999 as amended).
I trust this is of assistance to you.