Universities will sometimes make offers to candidates with predicted grades lower then the typical offer. I came across someone earlier today who applied for an AAB course with predicted grades if ABB, and still received an offer. It really depends on how over-subscribed the course / university is. You're two grades below, which probably doesn't make an offer terribly likely, but you never know.
Having one of your five UCAS courses be a bit "aspirational" is fine - just make sure than you also apply to some others with requirements which are at or below your predicted grades too.
As for what you can do to improve your grades, that's impossible to answer I'm afraid. You haven't mentioned what subjects you're taking, or what issues you're having (exam timings, subject knowledge, understand the question, matching the mark scheme, etc. etc.).