Also , would you expect a written feedback from your dissertation? All my previous assignments were accompanied by a report I have received together with the results?

As per the previous posts on this thread, it varies by institution and course. You should take a look at your course handbook.

In my experience, you get a paragraph of feedback on your dissertation if it's a taught MSc.

I got 68% and merit ..what does that mean in comparison with other no UK system!