Roughly how many circuits do you do in a one-hour lesson?
If you're having to orbit or park regularly then I'm guessing you're managing four or five, which isn't ideal. I found that my first circuit of the day was almost always dodgy, and it sometimes took three or four before I was well on top of things.
I'd typically do seven or eight in a lesson - and in about 10 hours of dual and solo circuits I orbited once, after catching up with a very slow Auster+Luscombe formation downwind - so it sounds like you're missing out on the part of the lesson that helped me the most. Sounds to me like a quieter environment may well help - mine isn't any cheaper, though...