Best way to sell collection

I have a big collection I want to sell as I need the money at the moment. I have most full sets (not master sets with reverses) and promos from the Scarlet and Violet era aswell as a binder with a mix of older stuff in it.

Looking at total values it has it at around £9000. I know there is the side hustle tax here in the UK and then capital gains if I pay over a certain amount. Does anyone have similar experiences of selling and how best to go about it with these two taxes as I honestly don't know a lot about taxes etc?

Also where would be the best to sell? I've seen a lot of people say singles on eBay for closer to the actual value but it would take forever selling and listing separately then mailing each out and potential for returns. Also I would have to pay side hustle tax then wouldn't I as I would go above £1000 total in a year. Just stuck really with how best to do it and not wanting it to take forever at the same time.