Changing degree subject totally in a gap year

Bear in mind English lit A-level and certainly a degree in English lit is not hust a course in READING literature, its a course in ANALYSING literature. Reading a text for leisure and reading a text closely for literary criticism aren't the same.
If you enjoy literary criticism/analysis though then it seems like a perfectly plausible option

Thanks! I actually really do enjoy analysis and end up helping some of my friends who take English with essays etc lol
Do you suggest waiting until I’ve got all my offers for stem degree to make decision? If so should I reject them now or just wait until results day to reject the choice and start the a level then?

That sounds like a strong indicator to pursue it then
That's up to you - if you know that you wouldn't ultimately plan to attend any of those courses you've currently applied to and are 100% certain you want to do the gap year then it's immaterial whether you get any offers or not as you don't plan to accept them ultimately. If you aren't completely certain then you don't lose anything by waiting until results day in terms of the UCAS application, although you'll probably need to start planning before then where you're going to do the A-level English lit course if you want to maintain that option.