Economics degree without Economics A level

Hi, I'm a year 11 and for my a level options I have picked Biology, Chemistry, Maths and Further Maths( I might drop FM if it's too hard).

So I initially chose these subjects as they were facilitating subjects and I liked and was good at them at GCSE. They also left my career choices very open and for a point, I decided that I would do either a medicine/dentistry degree as I like science and I also did work experience in a hospital which I enjoyed.

However, now I'm thinking whether I should really do Medicine/dentistry as idk if my passion for these subjects is to the top level.

In year 9/10 I liked the idea of Business and I've always liked Maths and have been good at it so my dad suggested the idea of Economics to me and I researched a bit more about it and I seemed to like it. I also like the idea of maybe studying it as a degree at somewhere like LSE or Cambridge.

However I don't want to take it as an A level as I feel that it would narrow my options. So could I still do it as a degree if I didn't take it as an A level. I know many university's websites say that Economics isn't required at A level for a degree course but I went to a school for an open day and a person studying there is applying to study economics, he said that eventhough universities say they don't need economics, they prefer it. Is this true?

He also said that if you don't take it as an A level you have to show passion for the subject. How could I do this? Like what kind of work experience, or extra reading or anything else could I show and have done in order to show my passion? Also I could maybe do an EPQ on it but then that wouldn't be useful for medicine/dentistry and they wouldn't consider it a 'suitable' EPQ.

Also is there anyone who did an economics degree without economics A level for universities like LSE and Camrbidge? What did you do to show your passion towards the subject?

Can anyone give me some advice?