So this is quite self explanatory but for some context I am in year 12 and I am currently taking maths,physics,geography and German as a levels but I also decided shortly that I wanted to do natural science or physics (at Oxford or ucl) however it’s a bit too late to change my subjects now so, I was wondering if doing chemistry or further maths in a gap year as a full a level (intensive year) after completing my other 4 a levels would put me at a disadvantage and make my application less competitive as it will mean I would take 3 years to complete all my a levels assuming I get the grades needed to go to Cambridge/oxford?
All the help is very much appreciated!!