This book is aimed at advanced undergraduates and new PhD students. It introduces the reader to advanced topics whilst maintaining the structure of a textbook which can be worked through be the student. Similar level textbooks can become a bit abstract, which means that they get harder to follow as you get into them, particular for a reader outside the usual academic environment. Here this problem is avoided by the use of examples from astrophysics to provide material for actual calculations, which help the reader to get to grips with the subject. The book starts with a rapid introduction to tensors, which might be a bit intimidating, but you don't really need to remember the symbolism to proceed with the book.
The book is nearly 700 pages in length and so covers a wide area of cosmology and physics. There is a section of the book devoted to quantum field theory, and you might find this a good place to learn the subject as there are plenty of examples of how QFT is used in practice. In particular those wishing to find out about Hawking radiation and similar phenomena will find this book useful. The author provides plenty of discussion of alternative ideas in cosmology, which will be of great benefit for anyone wanting to know why the 'standard' cosmological model is favoured over other possibilities.