I would suggest you contact the Universities you're interested in applying for, and see what they suggest - quite a lot of courses don't like you to studt too much before hand, but I imagine electronics isn't one of them.
Are your A-level grades high enough?, and in suitable subjects.
York for examples requires BBB for BEng, and AAB for MEng - and requires one to be Maths, plus a Science (presumably Physics would be best?), the third can be a Humanities subject.
If your grades aren't good enough, or the wrong subjects, you can do a Foundation course before starting the degree proper.