Not gonna lie I've got no clue where you heard that. I'm doing engineering at uni next year and grad jobs start at £35k - a regular job after that will start you from £40-50k. Thats already higher than londons average.
Trends seem to be up to £65k working for a good company as a regular engineer. Once you get more senior and start managing projects etc, you can make more than enough.
From work experience I've had, engineers are treated very well and respected.
You can always go into management or finance with an engineering degree - for example my course involves a module on economics and management in Year 2. Even without this, an engineering degree can take you anywhere (apart from medicine).
As you do research and have more experience, you'll figure out what you want to do. Engineering disciplines involve loads of maths. If you like how things move and mechanical systems function then mechanical engineering is good. Lots of that physics. If you like the theory behind stuff, lots of research, done on a much smaller level then nuclear physics is good for that. You've got loads of time till then anyway.