Ways for me to make some money over this summer?

Hey I'm not old enough to get a job as you can tell from my user flair, but I still don't want my bank account to read £0. Like I want to be able to walk into a shop, pick up something and buy it without feeling like I've spent 30%+ of my money. Ive done some car washing and lawn mowing but in the UK we are having another heatwave and I don't wanna stand outside pushing a mower around (also you can't wash cars in sunlight effectively).

If yall have any suggestions (im looking for maybe £20 a day) then I'd appreciate that.

Thanks in advance,

PG