CCE is really not a long way off BBB, you can definitely do it! (And certainly get better if you put the work in)
Make the best out of the mocks to know which topics you struggle in and which ones you are good at. Know that you can get some worthwhile information out of them on your ability on the topics
Frequently give yourself time to relax in order to de-stress, and remember people want you to do well (rather than be too stressed out and burnt out). If you really feel bad at sometimes just leave what you are doing at that moment and doing something completely different to help you feel in a better state IE go out to somewhere you like, do something creative, have your favourite meal. It does help
Also, getting small sections of work done frequently and attentively really, really goes a long way, I promise. As they say, Rome wasn't built in a day - the same goes for education
Onwards and upwards, take care