How difficult would a computer science alevel in one year be?

The Computer Science spec for OCR has recently changed; if you were on the old spec then the A2 exams next year are purely for resit students who have already taken the A2 exam this year. It would be possible to take the new Computer Science spec (H046) instead.

Whilst I agree with the above post that Computer Science A Level is not necessary to study Computer Science at University, the A Level does provide students with an advantage, for example if you already learnt Java at A Level and you are using it at University also. Maths is usually the "required" subject for CompSci at University (if that University has a list of required subjects for the course), so it would make sense to try and maximise your maths grade.

As for doing the whole subject in a year, it is definitely possible. However, there's the exam element and also the coursework element. It might be difficult to revise for the AS and A2 exams alongside the coursework, especially as the coursework for OCR (old and new spec) needs a coded program. It might be difficult to code a project whilst trying to learn the programming language at the same time, or with little experience of a language. For example, I had ~3 years of experience using Python, which made my programming project much easier to complete, and why I chose not to use Java as I only had experience with it for only a few months.

All in all, do what you think is best for you. If you feel that you can handle the workload, and you are committed to complete the course in a year, then you can certainly go for it . However, do make sure that you are focused and are able to handle both the Computer Science and the Maths resit in the year.