Oreo,
First of all welcome. I wouldn't really worry too much about not having an engineering or scientific backround. The level of Maths and Physics is pretty much at a level that you would have been subjected to at school.
The ATPL's are hard work due to the volume of subject matter you are required to absorb. You have pretty much hit the nail on the head when you say if you put the work in, you will be fine. Obviously, if you have an engineering backround you will have a head start, simply because you would have seen the material before.
All the best with it, and you will most likely enjoy it.