Hey there, my best advice is to think out of the box, focus on the elements of photography you are good at but then add a twist.
I did Eduqas A-Level Photography and for my exam I did Old Technologies as my theme. I focused on still life photography of retro musical media such as vinyl records, cassettes and CDs but created a deep, touching meaning of music being lost to time as they become obsolete. Which created my final piece consisting of vinyl records being half-buried in sand and bark.
At first I had no idea what to do also, but with help from my teacher and by progressing through my preparatory period, I had a solid idea for my final exam piece which I did in the 15 hours.