Original post by jestersnowHello,
So well done on the 1st class degree. There are some outstanding universities in the UK for Computer Science.
I would not put too much stock in academic rankings, as they tend to change and each of them use different criteria. As you say, there isn't much difference between 10th to 30th place university generally.
So I did 2 masters degrees and attended many open days and conferences over the years. Here are the following places I would recommend you check (aside from the obvious Oxbridge/Imperial):
Edinburgh: Outstanding reputation for CS, with a huge amount of modules for selection for your masters degree. Has very strong research areas in AI, HPC and Data Science.
Warwick: This would probably be a good masters if you want to specialise in data science, as they have a strong reputation for that.
Southampton: Has an incredible reputation and a world class CS department.
Bristol: Has a good reputation for CS and like Southampton, is very well regarded by IT recruiters in London.
UCL: Has a good range of postgraduate courses, but they are specialisms (e.g. HCI, Data Science). Has an overall good reputation, but London is expensive.
I would caution against certain universities that have an overall "excellent" reputation but have comparatively small CS programs. Durham, for example, has a strong reputation overall, but does not have the strong or big CS department.
There are also some Russell Group Universities that teach Masters in Computer Science, but they are aimed as conversion courses for students from other STEM subjects who did not study CS at undergrad. So they are basically undergraduate courses but they have the title of a Masters degree. It's probably not that helpful for you to study those. You would find courses like that in places like University of Nottingham, University of Newcastle, and QUB.