I've done ATPL Meteorology and after a while it isn't actually too difficult, despite being horrified when I first opened the (600 page) textbook, once you understand the basic concepts it all starts to fall in to place. But I really did struggle to begin with and had to go back to the start several times before it sunk in!
If you're halfway through the book and struggling, go back to the start and re-read the basic principles such as adiabatic lapse rates. I promise you, if you can really get your head in to these (try some online videos etc to see if they explain it better) then you'll find the rest of the book so much easier going forward. Also when you read something, sit there and try to make a picture in your head that sticks.
For starters, here's a pretty good simulator for helping you to picture how different pressure/temperature settings affect the altimeter reading
luizmonteiro - Online Simulators - Altimeter Errors Simulator. I think that the first thing for any new pilot go get out of their head, if you've not done so already, is that the altimeter tells you how high you are, it doesn't! It
only measures pressure and then indicates this on a scale according to a set of pre-determined average set of conditions, ISA. If the conditions are not ISA (almost impossible at any one place at a particular time), then the altimeter will not tell you your True Altitude.