hionestly don't worry. VAt is much simpler than you might think. Don;t worry about reclaiming old stuff just start accoutning for VAT on the day he becomes VAT registered and your VAT package should calculate your VAt payment for you and probabaly even print out a return (or at least print out what you need to write on the return).
If your boss wants to reclaim old VAt he can pay someone qualified to do it.
With my dad for example- removing a memorial for burial is zero rated (as it's a necessary thing and not a luxury), most of the funeral is zero rated but the gravestone and flowers and things like that have VAT on them. Dh sells IT equipment and there are little idiosyncracies there. Second hand equipment differs to the new stuff. Personally I'd ringt he VAT office and have a chat