Since I'm from Colombo (not form UCSC as in our times there wasn't anything like that... I did sp degree in CS in dept. of CS, UoC which is now renamed to UCSC), I will try to be as much as unbiased towards UoC
As far as I can tell you, it is not actually the degree you have matters. UoM Computer engineers, IT graduates, UoC CS, BIT graduates, OUSL graduates, SLIIT graduates, IIT graduates, etc... are all coming to the same job market of software engineers. The point is that you have to perform well, not only theoretically, but also piratically to get selected to good companies. If you have good results, but your application skills are low (this is a common case with our freshers), it is not easy to select or maintain the job. So be a practical person. Try to understand the theories you learn with practical scenarios.
Choosing UoM or UoC is completely up to you to decide. Both universities are high standard technical universities. You might pay a visit to both faculties to see the facilities, etc.... and decide yourself. As far as I know UCSC is super in terms of facilities, lecturers and more importantly the university culture.
Before entering university what to study..... As I can tell you, spend time to learn some English. But don't worry too much as when time goes you will learn to cope up with it. Having some knowledge in programming (based with a language such as Java) would be advantageous, but not important as lecturers will start from 0. Note that there is no need of going to tuition classes as you did for A/Ls. You will be taught everything and be given a list of references (books) to learn extra things all by the university. So do not think too much, since you will definitely get all these from there.
University life is fun. There are so many other things you will experience there such as how to behave with different types of friends coming from different cultures.
Remember to discuss the "culture" thing that I have just told you about UoC over other universities (especially dept. of CS -> now UCSC). That's something I enjoyed the most.
Good luck and ROBOT.LK will help you out if you find any problem !
