Applying for Computer Science

I am currently applying for a Computer Science course with predicted grades of A*A*A* in Mathematics, Physics, and Computer Science. However, I only achieved b in AS Level Computer Science. Will this grade affect my chances of receiving an offer when the admissions office considering my predicted grades?
Also, I'm currently holding a 4 in AP(Advanced Placement, a test held in USA) Computer Science test, will the admissions office consider this score as a corresponding A Level grade?

With regards to AS levels, some universities take the view that as not all students have the opportunity to take AS levels (for subjects they're taking at A level) it would be unfair to include them in the decision-making process. Others take the view that any and all information about your academic record is "fair game" and will look at your AS grade when deciding whether to make an offer or not (and whether your predicted grade at A level is plausible).

You'd need to check the admissions policy for each of your target unis to establish the approach they take.

With regards to your AP grade, I'd be surprised if they did. Even for UK qualifications, the universities you're likely applying to with those grades rarely draw a direct equivalence between qualifications. I'm not saying that they would ignore the AP grade, but they're probably not going to directly equate it to an A level.