CGT calculation

I have a situation where the probate value of 1/3 of a property ( and part of the estate ) was valued at approx. £780,000. This was valued by a RICS surveyor.

The share of the property has achieved far in excess of this sum , approx. 1.2 million

Do members have any advice in relation to this . Can I just pay CGT on the increase in value at 28% . If so are any particular forms required.

I imagine HMRC will involve the District Valuer given the increase but any advice would be gratefully received.

Many thanks