I have been chatting to the nice people at the Croydon SVA test centre and they told me that the 2 main reasons why people fail are sharp edges and wiring. So:
1: Make absolutely sure that there are no sharp edges anywhere!(just in case) and
2: Use lots of conduit for the wiring, they like that!

Also i was told that waiting time is down to about a week, at Croydon at least.

Andy