Paul W and I did mine at the Mitcham SVA shop and on the way back stopped at DVLA Wimbledon to have the car inspected by them (Middle of Wimbledon fortnight so traffic was stupid) - they needed to see the Chassis number stamped into the chassis - pointed out where it was and they decided not to even climb on the trailer to check - ditto for the engine number!
But they were not happy doing this and wanted to send their inspector to our property for the inspection. We chose the route we did as it was very time critical for the LM Classic in 2006 and it paid off.
After that they took all my receipts for the major stuff chassis, brakes, engine. box, instruments and kept them overnight before issuing an 06 plate and depletin my account with about £250 for their troubles. (I had a carrier bag of receipts for screws, filler, fluids etc that she did not want.)
Tell the DVLA you want a new reg and not a Q and so long as you have the necessary paperwork to "prove" newness they will oblige
It is not rocket science but just need loads of patience to deal with the Govt departments (patience is not my strong suit)
Ian