hold on. i use the smith squat machine for jump squats. so i dont end up jumping and falling over. is this ok?

Thanks for that although there was some parts that i didnt really fully understand. Looks like i'll be trying to stay away from the smith machine now although i'll have to use it for bench press a bit.

I am now really thinking of trying to get a squat rack, bench, barbell, dumbells and weights at home now so that i have the right equipment. I just need to convince my parents that we have the space and money to do it.

The question becomes "why are you using jump squats?" If you're using them as a pseudo-plyometric for sports training, then you shouldn't be using anything to stabilize your body (that would defeat the purpose of improving balance in an athletic activity). If you're using them for hypertrophy, they might not be the most suitable exercise (plyos aren't really very good for "bodybuilding," at least not when compared to more traditional means). You can use explosive movement without leaving the feet and getting airborne, so you should consider the purpose of the exercise.

Having said all of that, the answer is still no, for the same reasons that performing a traditional squat in the smith machine is bad for you. In fact, learning how to land with balance is a fairly vital athletic activity (think of how many sports, especially basketball, volleyball, certain positions in football, soccer goalies, etc, etc, that require the specific skill of jumping and landing with balance in a squat-like position). Don't use the smith!