Which of those level 3 subjects would most likely help me towards Elec Eng/life in general?
Can I apply any of this knowledge directly to everyday life? Would any of them open up opportunities in Financial Mathematics? (Finance is my breadth stream)
Just saw this question. If you can manage it, I'd suggest Applied Mathematical Modelling and Complex Analysis. Electronic engineering is big on complex variables and if you've done complex analysis they'll be a whole lot less scary and a whole lot more "I get how this works". The Applied Mathematical Modelling course builds on differential equations to model real-world problems like traffic flow and fluid dynamics; I haven't done it but I've heard good things from friends who took it as an elective in their MSc.
And then if you've got room left in second year and want moar maths, you could do either Discrete & OR or Prob & Stats, depending on what excites you more. OR is probably more applicable to engineering.
As for application to every day life, I'd say the best thing that a pure maths degree has given me is practice in thinking like a mathematician: breaking down complex problems into abstract concepts and being able to reason precisely about them. Totally relevant to any kind of science or engineering.