Maths and Physics are necessary, though in some cases you can get around not having Physics. Further Maths is near-necessary for Imperial and Oxbridge, but if you don't want to do or can't do FM that's not a major issue because there are plenty of other universities which provide engineering degrees of equal quality and don't require FM. I'd say anyone who says FM is necessary clearly hasn't started an engineering degree, or has gone to a university with a poor idea of what maths skills are needed for most engineers.
For your other subjects do whatever you want, I'd recommend doing a language because it will open up a lot of opportunities at uni but other subjects are good too if you're stronger in them.