A few thoughts..
VAT de-registration can indeed be a fairly simple process. However, you can only de-register once your 12-month rolling turnover has dropped below Â£58,000. You cannot de-register on anticipation of this actually occurring in the future.
As far as stock and assets are concerned, if the VAT-inclusive value of the stock/assets is less than Â£6,714 then you do not have to account for VAT on them.
You do not have to include any stock/assets that you were unable to claim input VAT on. Incidentally, you could have claimed back the VAT on stock purchased prior to registration on your first VAT return.
Remember that the valuation includes business assets as well such as computers, fixtures, office furniture etc.
Such is the nature of valuing second-hand items, the Revenue do not expect it to be completely accurate. However, if you are going to be close to that Â£6,714 figure I would recommend doing a stock take.