Well, today I finally got round to changing the code that DJCruicky suggested, which was a bit tedious but in the long run that will help me greatly. It will certainly save some headaches when it comes to adding a second player.
In addition, I think I've sorted out the 'fruit appearing in platforms' bug, and I also hope I have fixed the score problem Predseda pointed out (it happened to me this afternoon for the first time) but only time will tell on that one.
Big thanks to Wilshy who has kindly volunteered to produce some sound effects too. As soon as I get them I'll work them into the game. Everything's looking good at the moment.