Hi Stephen,
The kit build instructions are available as a download from Taimya USA, here: **LINK**.
If you already have those (they should have come with the kit), and are looking for yet more detail, I am not aware of anything that specifically addresses building that particular kit. You might find discussions of the kit on the various plastic modelling fora that abound on the net.
However, the Vosper Perkasa is, I beleive, a fairly popular subject amongst modellers, and I am sure that some clever googling might turn up lots of more generic stuff. There is for example an enthusiast website dideciated specifically to this boat at http://www.perkasa.co.uk.
/Mattias