Hi User0325,
You've already had some really good advice so no need for me to repeat it. My first bit of advice would be not to worry. You've done your exams and so have done all you can for now, and you know you are taking a gap year and so this should remove any worry about deciding what you want to do next immediately.
My recommendation would be to see what your results are come August - its perfectly normal to feel nervous after you've finished but if you've put the work in and been organised then its likely you will have done better than you think. Depending on what those results are, you can decide whether you'd like to retake any new subjects, however if you are happy with what you achieved, it may be easier for you to simply use your gap year to work part-time, travel and start doing a bit of thinking and research about what you might want to do next.
If you are naturally creative and have a talent for art, there are many courses which you may not need specific A-Levels in and will consider you based on your personal statement/portfolio and other things you have done with your art. You are also not confined to Fine Art - you could also consider something like Graphic Design, Design for Visual Communication, Fashion Design if this is more you, or even something a bit more business-ey such as Marketing which also has many creative elements.
One of your options would be to apply with your results in the main cycle next year after spending some time saving up some money, visiting open days and exploring your different course options - if you have achieved results you may be eligible for unconditional offers which will also take an element of stress away.
I hope this helps and best of luck with what you decide to do next 🙂
University of Bath