I have a similar DD. She is considering a career path similar to mine which I am happy about and which I think will suit her. The other DD is an entirely different proposition so I think it is horses for courses.
I am a retired chartered accountant. The things I miss most about working are designer suits, heels, glamorous travel and entertaining intellectual companionship at work. It paid so well I retired early to focus on other commitments. Also I did not think it possible to work enjoyably at less than FT 100% commitment at the top flight of the profession. If you are not prepared to outsource the rest of your life or compromise your career then this is a consideration.
I agree the non university route is perfectly valid and the big firms do recruit from school. However doing a University degree first is more fun and gives more options later on.
My degree is Law and Economics. It would also have given me entry to law, banking, management consultancy, civil service and numerous other paths. I have legal friends who are corporate lawyers, university professors, policy advisers, merchant bankers, and traditional law court lawyers, advocates and judges.
I have accountancy friends in chief executive as well as finance roles in fields ranging from investment banking to the charity sector. Training with a big audit firm gives access to almost all industries (even music) and there is plenty of opportunity to explore different options and develop specialisms as you find where your interests and talents are best suited.
I agree to earn the highest money and have the greatest career impact you have to be prepared to go to where the work is which is the major finance centres and the top jobs are more concentrated in these areas than they used to be. Plenty of opportunities to work internationally.
DH is an IT consultant. He also has had opportunities to work in a multitude of industry sectors and there are options which pay very well. His career is more flexible and as a lot of it can be done remotely it is easier to be well paid outside London. There is also more opportunity for home working etc. I think he would advise a Maths / Science degree rather than an IT degree as the entry route to give the best opportunity for career progression.