A level choices for studying medicine

Hi, I'm currently in year 11 and I'm struggling to choose my A levels. So far I have chosen Maths mechanics, biology, chemistry and physics. In the future I would like to study medicine, however, for some uni's such as UCL, I heard that they would like 3 relevant subjects and 1 contrasting subject. I have contemplated on whether or not to change my A levels to Biology, chemistry, art and maths statistics instead, is that a good idea?Also, I would like to become a sports doctor one day or something along that route and I just wanted to know if my (mock) GCSE results would be good enough as I am hoping to do better in the actual thing. My results are:
Art - A*
History- A
French- A
Economics- A*
Biology- A*
Chemistry- A
Physics- A
(IGCSE) Maths- A
English Lit- A*
English Lang- A

Sorry this is a bit long but all the advice/ help would be much appreciated, Thank you
p.s To become a sports doctor would i need to do a degree in medicine first and then a MSc in sports medicine and exercise medicine or is there another path?

Biology + Chemistry + 2 others which you enjoy and think you will do in. Maths/physics are not necessary.

As for being a sports doctor - yes, a medical degree is a must then you need to specialise (an MSc would be useful here - no one will look at your GCSE grades). Traditionally I believe sports medicine was practiced mostly by GPs and orthopaedic surgeons with a special interest in the field, but it appears that there is now a dedicated postgraduate training pathway. More info here:

https://www.medicalcareers.nhs.uk/specialty_pages/medicine/sport_and_exercise_medicine.aspx

Maths, Biology and Chemistry would be sufficient (and very good) for Medicine, then go for a 4th you'll enjoy. Art is a lot of work, remember your other subjects will need to be focused on strongly as well.