From what I know A levels can be pretty challenging, if you're pretty motivated and good with managing your time and staying focused you could, what I'd suggest is with your a level choices and GCSES maybe consider doing a mix of both coursework based subjects, performance based and exams just so it all balances out. Pick the subjects dependant on what you know you will be good at - I thought A levels would be for me but I ended up doing a BTEC Extended Diploma Level 3. I think it would be hard to do in one year, but the GCSES could be done in like half a year easily but not too sure about the A levels