Usually CS degrees assume no prior background in CS or programming. However they do very commonly require a background in maths to A-level standard, which you don't have - however not all courses require this. I'd suggest checking the entry criteria to be sure.
In terms of workload, all degrees are, essentially, the same amount of work. This is the point of them using a standardised credit system - 15 credits is worth the same amount of work regardless of the actual course studied. While the exact break down of contact hours vs self study hours may vary, the same relative effort is required.
So changing your subject because you think another one will be "less work" is going to backfire, because you still need to put in a similar amount of work to do well. In fact, for non-AHP subjects you have to do more work, because you need to be actively seeking internship and placement opportunities throughout the course to make yourself employable (whereas generally for AHP courses, provided you are flexible in where you work, you will be able to find a post in the NHS somewhere when you graduate, as most AHPs are in shortage at the moment).
You may want to consider if university is the right route for you if that is a concern, and whether an apprenticeship path to qualifying in your desired field (either in the computing sector or in an allied health profession - both have a variety of apprenticeships up to and including degree apprenticeships) may be a better fit if you think working and learning suits you better than primarily or purely academic study.