tomcs,
Bookworm, WCollins and Vintage ATCO are 100% correctamundo...
If you fulfill the requirements of AIC White 76/2003 to the letter, you need not get written permission.
If you do not fulfill the criteria exactly, then you need to speak to the GA Department at the CAA. Apparently, the number has now changed to 01293 573510 as I found out recently after trying to get somebody on the other number for about a month!
I'll second the fact that they are incredibly helpful, which for the CAA is quite a thing!