The London system book
There are 23 ratings and 5 reviews on Amazon and a selection from the book.

Only you know where you stand with regard to the opening.
What did you think when you read the selection?
My guess, only from looking at your ratings, is that it would be very advanced for you.
At your rating, I would strongly recommend NOT buying and reading any books devoted to specific openings. Read something on general opening principles. That will be more than enough for now. You need to work on tactics, tactics, tactics. That and play a lot and review your games afterward.