Hi James,
The date of disposal is the date of completion and not the date of exchange of contracts, which will be before any confirmation from land registry.
CG34 is an optional, free post transaction valuation service, which you may use to validate the value of the property used for capital gains tax and inheritance tax purposes.
(
CG34 — Post-transaction valuation checks for capital gains).
How you arrive at the value is up to you, but you could not use a 1 year old valuation.
The valuation would need to be based on the property at the time of disposal.
Thank you.