Hi Jonathan & Vanish - using the accrual date function does work with a new business, ie where you don't have pre VAT bookkeeping. If you do have pre-VAT bookkeeping however you have already recorded the asset in your books and so this would effectively create two assets in the books, one gross of VAT and another net.
In this case, all you really want to do is take the VAT out of the original cost of the asset and putting it into the VAT account to claim it on the VAT return. This is best achieved either by using a journal entry on the first day of the VAT period or, if you are not familiar with Journals, by using your existing, or even a dummy, bank account to record (on the first day of the VAT period) money in & money out for the total cost of the asset, as follows:
Using a total cost of £2,400 including VAT, you'd record money in for £2,400 with no VAT, to the asset account and then a payment out of £2,400 including VAT at standard rate again to the same asset account. This would leave the asset account depleted by £400 and put £400 in the VAT account to appear on the VAT return.
@Vanish - it would be nice to see a "pre VAT claim" function but because it needs to cope with the above two scenarios, it think the workarounds are probably more realistic at the moment.