You've been very receptive to everyone's advise so far, so please keep listening.
First, as everyone has stated, the cage you have now is not going to work for you. It's way too small, even for a baby cham. They grow VERY fast and that small of an enclosure will not work, even if it was free.
I understand that you want to get this cham and you are excited, but you need to get everything you need BEFORE the cham. If that means waiting until after summer when you've made your money, then as a responsible keeper (and person in general) that's what you need to do.
Finally, and I dont think a lot of people have pointed this out, if your father is incapable of respecting the boundaries of your pets enough to NOT handle them when they dont want to be handled, then maybe having a chameleon when you are still living at home isnt the best idea. Handling can cause a. Lot of stress for chameleons, and continued, constant stress can and will eventually kill them.
I know you clearly want to have a cham, and I understand, they are beautiful and fascinating creatures. But if you really love them like we all do here, then you need to take all these things in to consideration. Being a responsible adult sometimes means putting the needs of others (including and especially animals) before the needs/wants of yourself. Like I said in the beginning, you've been very receptive and understanding for everything weve told you up until this point which is very demonstrative of your personality, so I think you'll make the right choice here. And I also think down the road when you are completely ready you will make a great keeper.