Take a few tools with you as its common for the headlights to be misaligned and make sure that the wheel nuts r all tight.
Class 7 MOT is incorrect its a visit to a ministry testing station every year my missus works for a truck repair company and they took all the RB44's for testing at a ministry testing station. Which was another reason why I wasn't bothered about the 'brake problems' I got the info direct from the mechanics who repaired the vehicles.
If you take it anywhere else for the MOT the DVLA can invalidate the MOT certificate when you go to register the vehicle for the 1st time and you won't have any pennies returned and will still have to go for a ministry test.
Best thing to do is ring them up and ask and let them talk through the procedure for the 1st MOT. I found them very helpful same with the DVLA in Manchester. I printed out pictures of the chassis and axle weights when I sent the forms into VOSA.
Axle weights by the drivers door next to the chassis plate.
Don't loose the cast certificate as its the only one that you will receive from Withams.
Take everything with you including the plating certificate when you register the vehicle on the V55. Don't forget a valid form of ID passport or driving licence, utility bill, insurance certificate, cheque book and a friendly face. Basically what ever they deem necessary to get it registered. Friendly face isn't on the form but it does help