Hi Freya109!
I am currently a year 3 Ravensbourne student, and I understand that you are trying to keep your options wide and chosen academic subjects such as biology, geography and English.
That is a good way of thinking, however also remember that as you are trying to cover a broad area of study, it can also become less effective towards very specific courses such as interior design which is a very creative based course.
My advice is that by taking an A level in an art based subject you will have that as further support for your portfolio. It is great that you are thinking of a range of courses you can do, you seem open and giving as many choices to yourself as possible, so why not take an art based A level and continue giving yourself more of a fighting chance.
Like you, I also studied academic subjects maths, physics and psychology they are very science based topics but i always considered art on the side. Despite my heavy science based A-levels I had chosen Art at the very end having completed my art foundation and now study animation.The 2 years in A-level made me realise that I wanted a more carefree lifestyle, had I chosen another topic I may have been drawn towards another path.
You find that the more you study a subject the more you realise whether you want to continue pursuing it or dropping it, these all help towards your final decision, going into a creative industry they often want to see passion and that is why a portfolio is so important, often we are building upon ourselves inside and out of class. It is the consistency that interviewers want to see reflected in our work. I understand if you want to pick up another A level in substitution to keep your options open, but also consider the benefits of taking textiles further.
Although it is not technically required, some unis and courses may expect you to have an A-level in a relevant subject area
In order to be on the safe side, make sure you look at the requirements of the unis and foundation courses you are interested in and when in doubt contact them and check beforehand.
Give yourself the best chance possible, the more you know the better!
Hope this helps
Jay