I graduated in 2005 from the Avionics course and have been working in the south-east of England since. I was recently involved with the department providing feedback on the new proposed degree course. To be honest, there's not much Avionics actually involved (albeit a 4th year course entitled Avionics). You get the best of the Aero courses, and there's a hefty bit of work from Electronics and Electrical Engineering involved, so you have to be very adaptable! Flight mechanics one hour, and then switching to electronic circuit design the next!
Unlike the Aero course which includes some non-engineering modules, due to the collaboration between Aero and EEE for Avionics, it's completely engineering based. The result is 4 years of solid engineering. It's not easy and you'll find a lot of your peers will drop out after the first few months to a year so be prepared to knuckle down and get stuck in early.
Best of luck with the choice.
If you've got any more questions, I'd be more than happy to help
Mc