I’d just like to emphasise Jeremy’s comments. Ultimately it would be good to aim to get some filters but proper photometric filters are very expensive and a lot of work can be done without them or even using the much cheaper filters designed for colour imaging.
If you are interested in trying something slightly different you might want to look at our project to monitor the comet 29P/Schwassmann-Wachmann. Have a look here for details. This comet is well placed at the moment and normally sits around mag 16-17 but it can flare up and catching the eruptions early is very important. Richard Miles runs this project on behalf of the comet section. It might be a little faint for your kit but try some images of the field and see what you get.