Selling Collection

Hello. I am looking to sell my card collection. I think the value could exceed the £6000 value I have seen on some capital gains rules but then its also if its over £3000 profit. If its over £6000 would I have to prove its not over £3000 profit? As i said I started this collection in 2019 and so it may be hard to prove how much I actually spent. I was just wondering if i could get some clarification on requirement if I do sell it for over £6000 please?

Hi,
Please refer to Personal possessions and Capital Gains Tax 2024 (HS293)
Thank you.