If I were you I’d definitely start 4 but have the intent of dropping one after a while when you decide which 3 you like best. Doing 4 A-Levels means your timetable will be a lot more full and you’ll have less free lessons where you can do homework & further reading, which I’ve found to be incredibly useful. Some girls in the Year above me (year 13) wanted to take 4, but now literally less then a year before their A-Levels they have both decided to drop one and only take 3, as it’s too stressful, especially when you will have UCAS personal statements to write and other possible things like a part-time job, driving lessons, EPQ, volunteering, work experience and depending what your Sixth-Form is like, you might want to become a prefect or apply for Head girl/boy (or deputy head girl/boy). Doing 4 A-Levels isn’t impossible, as there was a girl 2 years above me who achieved 4 A*s at A-Level. But then again, she did 11 GCSEs and achieved A*s in all of them. If I were you, I wouldn’t completely get rid of the idea of 4 A-Levels, but I just want you to know that it will be a lot more time consuming and a lot of work. If the University you want to go to doesn’t require 4 A Levels (I’m pretty sure than no Unis require 4 A Levels) then it’s a lot of extra work and effort to be putting on yourself, when you’ll already have enough with 3. University’s much prefer to see a set of 3 A-Levels with high grades, than a set of 4 with average grades. I hope this helps, and sorry if it sounds a bit pessimistic! I’m just going off advice that teachers, my parents and students gave me at the beginning of this year, as I wanted to take 4 A-Levels in Maths, Chemistry, Biology & Physics, but didn’t end up taking Physics in the end.