What should I do in Y12 Summer

For reference I am studying A level Maths FM Physics and Chem (A*A*A*A* prediction) GCSE 99999999988 (8 in FM and lit) and my target/ reach unis are Cambridge natsci physical and imperial physics. For this I need to take the ESAT (probably maths 1,2 and physics because that is what imperial needs). I also have extra time (25%) for the esat which I think helps because it is time pressured.

I was wondering if anyone had any advise on how much time to spend on esat prep and other stuff during the holiday as I am kinda lost. Also there doesn’t seem to be that much online for esat prep.

Also to prep for interview and personal statement I’m supposed to do some super curriculars but I’m unsure what is worth my time and what isn’t. For reference I’ve done John Locke essay comp, wrote an essay on using relativistic and non relativistic math to determine the end of the periodic table, was team lead on a team that won the cansat engineering excellence award for on site performance, and some other smaller stuff like bpho online gold written silver and a couple other physics competitions like physics brawl (1st in uk for category) etc. I’ve also done work experience at imperial materials lab a spine robotics company and another university in my home country (I am a UK home applicant though). Is it worth doing a bit more like more research into the paper I wrote? Also I’m a decent chess player (2300+ chess.com) but idk if this is worth talking about because it’s not really relevant.

I should probably look at some of the next year a level content aswell right?

Thanks for reading and any advise on my application would be much appreciated.