How to Cold Email for Work Experience as a 6th Former / Final Year High School Student?

I'm in my final year of school and am looking for some work experience in the summer before I leave to go to University. I was planning to cold email different small hedge funds / local PE firms where I live and in London and was looking for some advice on what I should say in my email, as well as what I should include to make myself seem credible.
I've got an offer for LSE Finance (pending A-Levels), have done some work experience at an Investment Manager (£50bn AUM) (done through an application, not cold email) and do some investing on the side. Although I have no idea whether I should include any of these, my CV or anything else.
Thank you in advance for the help.