The Ox books are very good. But then again, so are the notes for most of the JAR ground schools (the format varies but when you read, the content is within IR tolerences of each other).
Why not buy the ones for the subjects where you have the gaps from the Bristol course?
This will save you tons and allow you to focus on areas of weakness.
When you pass, you can sell then, or rent them to Ppruners asking the same question next year.
(being a generous soul, I just lend them out, but before you ask, they are out at present...)
h-r