Hi in my opinion if you're not sure what to do I'd take Triple science and humanities (like history and geography) as they're quite broad subjects and have skills that are transferable to other subjects e.g. essay writing and analytical thinking
However in the grand scheme of things GCSE's are not that important (thats not to say they're not important as you need them for A-Level) so just pick things you enjoy doing because when you decide what you want to do it will more than likely surrounding something you enjoy doing.