Nocturnelover: Those plastic keyboards are horrible, it really will hold you back, you should find some other way ASAP! Henrah has a good idea in asking for a key to the piano, you could also offer in exchange for use of their piano to maintain it, keep it clean, call in the technician when it needs repairs or a tuning...
You'll still want something decent to practice on at home, your best bet is a digital piano. It's still not the real thing, but it's much more useful than a cheap plastic toy. Look into ways to get ahold of a digital, get a part time job, do chores around the house, anything to make a buck and it won't take long before you have enough money to buy one.