Been there, done that sucessfully albeit a few years ago (2017) with a second-hand quad. There are other posts on here about this topic so do your research, there is a lot of good info on this forum.
As others say, getting advice out of DVLA is challenging to say the least. This is a copy of my second letter to DVLA from 2017 listing the items I had provided:
DVLA
SWANSEA
SA99 1BE
February 2017
APPLICATION FOR A VEHICLE REGISTRATION CERTIFICATE – HONDA TRX420FA VIN: XXXXXXXXXXXXXXXXXX
Please find attached for your consideration my second attempt at registration of my Honda TRX420FA quad (VIN XXXXXXXXXXXX) that I purchased used for use as a light 4-wheeled agricultural vehicle in connection with my duties as a keeper on 2 shoots and a deer stalker. I am applying for registration and first issue of vehicle tax as an agricultural vehicle for use as a working vehicle used in conjunction with my responsibilities for the raising of livestock and the management of deer.
I have attached the original “age-related” letter provided by Honda in respect of this vehicle, a copy of my purchase invoice and a copy of Honda’s EU Declaration of Conformity supplied with the vehicle. I have also enclosed proof of identity (driving licence photocopy), my third-party Certificate of Insurance (and schedule that provides a link to the vehicle), an off-road certificate (not sure if this is correct) and a cheque for £55 which I believe is the correct amount payable. I certify that since acquisition on 5 Aug 16, the vehicle has been exclusively used off-road to carry out my livestock rearing duties.
I have found the registration/taxation rules not easy to follow and if I have omitted anything in support of this application, please do not hesitate to contact me directly.
Yours sincerely
Full Name
Enclosures:
1. V655/5.
2. Cheque (£55) Serial Number 100274.
3. Honda Age-Related Letter VIN XXXXXXXXXXXX dated 2 Sep 16. Obtain this from the manufacturer - Honda was straightforward!
4. Honda EC Certificate of Conformity TRX420FA VIN 1HFTE37E*4QA100001-109999 dated 20 May 09. This was in the Honda Owners Instruction Manual
5. Copy of Purchase Invoice for Honda TRX420FA VIN XXXXXXXXXXXX dated 5 Aug 16.
6. YYYYYYY Certtificate of Insurance and Schedule (Policy No ZZZZZZZZZ). I included the schedule as it listed the VIN whereas the Certificate didn't
7. Off-Road Vehicle Declaration. I found this trawling through the DLVA website - not sure if it was essential
In due course an authorisation for number plates and a V5C was forthcoming. There was no need to take the vehicle anywhere either to establish it was what I purported or to do any form of MOT. The VRN they issue cannot be changed so I was unable to subsequently put on a personal plate I was holding on retention.
PM me for any further details.