I was in a very similar situation to you, studying a physical science rather than engineering but first year is tough and its designed to be that way. Getting the right balance between your social life and work is something very few people master in the first year especially at UK universities.
Having the degree and the experience will help in a lot more ways than just learning your course, also the ability to work things through when it gets tough is an invaluable skill. I consider myself lucky that the Biology course I was trying to transfer over to was full (thats how close I was to re-doing first year).
Losing your medical can spell the end of a career and having that safety net of a degree will be incredibly helpful in a worst case scenario. Besides that, the salary you will be on after graduating will mean that you'll be able to save up for training in a much shorter time frame.