Engineering and Science in UK and Europe

Check out the Times Good University Guide for college rankings in the UK, I believe Oxford and Cambridge both have science and engineering courses. For prestige, it's difficult to beat either.

Cambridge is probably the strongest in the UK with Oxford not far behind.
Imperial College London, Bristol, Manchester, University College London, Southampton.
Which particular speciality? There are some small departments that have outstanding reputations in specialist areas.
Paris in France, ETH in Switzerland, Leuven Belgium. Lots of places in Germany - though these will not be English speaking.