Hi there,
I am currently on the Software Development MSc program. The first semester all 3 of the courses do all of the same classes, generally if people are on the software development track and do not perform well or feel confident enough in the programming they are advised to switch to information technology (advanced programming is not meant to be much fun if you found the introductory programming hard). At the end of the first semester you can switch between any of the 3 programs, and if you are studying the IT program and decide you want to do software development you simply take the comulsory software development courses.
You are very likely to gain entry, there are people who have studied English Literature, History, Engineering, Business, Sports, just a huge cross section. As long as you have the 2:1, at least if it is like this year, then you should get on.
Yes you can go straight onto a PhD depending on your performance and interests, although you must apply fairly early into the 2nd semester when you have a lot of deadlines so perhaps it would be best to ensure you have this done in advance (say over the christmas break). I know of at least one person who is going onto the PhD track and we were all told any of us would be able to if we could find a supervisor and had the ability.
Regarding employability I personally got a job offer in the first couple of months of the course at an investment bank, the interview process was open to graduates of any degree discipline so did not focus heavily on programming experience (thankfully). Others in the course have said that application processes or interviews to other establishments did ask a lot about programming, data structures or algorithms which they could not answer at that point and so they are planning on applying at the end of the course. To be honest after about half way through the first semester the work load is very intense and relentless except during the christmas break. I would say the best chance is applying to graduate schemes open to any discipline (these are still with huge companies, e.g. IBM, Accenture, many banks) or wait until the end of the course when you can prove your ability.
I think professional development is huge in the IT industry, but I don't really know how much employers immediately will care if your course is BCS accredited over your ability. Potentially this sort of thing is for further down your career to prove you are interested in continuing professional development, or an ego boost of another certification or Chartered status (but I do not really know as I am still just a student).
Also the course director can be pretty slow to get back to you, a lot of people on the course had the same issues before starting
I hope I have helped and if you have any other questions ask away!