Can certain legal costs be deducted from CGT on a property sale

We've just exchanged contracts on a flat sale and I'm starting to think about CGT on the proceeds. My question relates to a previous, failed attempt to sell the flat in 2022. At that time, we were obliged to pay £4,000 for a Deed of Variation to the lease. Is that a cost which can be deducted from the proceeds of the flat sale to reduce our CGT liability?

PS I probably should have added that the flat is a buy-to-let property, ie not our main residence.