The LHC is in Switzerland (not the UK) and in fact I'm still here. I was a data scientist for while. These days I'm back in research, but in a different field.

There is a huge demand for CS skills of all kinds. CERN has one of the largest SCADA installations in the world, runs its own internet exchange point, operates a network of computing centers with a million cpu and hundreds of PB of data, and maintains many many millions of lines of code of specialized software, just to give you an idea.

It is a fantastic place to work, the level of expertise and dedication among the people there (scientists and engineers alike) is very very high.