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.