getting vin number

[andbolt0]

can any one point me in the right direction regards geting a vin/chassis number for a project bike it has a new hardtail frame and parts from various other bike  i want to do this the right and legalway so i went to local dvla office before it closes and was given form v55/5 (titled APPLICATION FOR A FIST TAX DISC AND REG OF USED VEHICLE) wich i dont think is the right form and was told to send an acompaning letter asking for vro chassis number and Q plate any help would be greatly recieved thanks in advance andy

[Olds]

Things may have changed but I filled in form 627/1 Built up vehicle report and sent this with an accompanying letter asking for a VIN to DVLA.
Been looking on the new GOV.UK vehicle registrations site and it is as clear as mud. They tell you why you may need to apply for a VIN but not how to or what forms are required.
When dealing with DVLA it is a good idea to make copies of everything you send and I also send recorded delivery.