Hi,
You are only due the capital gains exemption in the year the asset is sold. The guidance you are referring to is to let you know that as executor, you are allowed to claim the allowance for a limited period of time to allow you to finalise the estate.
Selling this year would mean only £3000 exemption is due on any gain made so if any tax is due you still need to report this:
Report and pay your Capital Gains Tax
For any other income received in the period of administration, you can write in with the details.
Thank you