I would hope that doing a PPE and meeting fascinating students and tutors will open your mind even further. You might even invent your own future version of Apple/Whatever. (In which case, GGL is irrelevant as you will become Premier.) You might decide to become something completely different. Teach First??
Keep your options open...................but know that the competition for your dream job will be selling themselves to that great employer from day 3 at Uni., so open options, but an intent to compete for the best jobs is required. (Why Day 3 . ?? Day 1 is beer, day 2 is sex, and day 3 is sector/profession and employer hunting.)
Intern work is something you need to investigate carefully.
If, after 3 years of mind expansion, you still do want your employer to pay for you to fly a lot, follow frandrake's advice. Get a job in a global top 3 or 4 Company, which is in a sector with high gross margins, and seek to make the job Global. Sectors such as Pharms and Oil will continue to have high margins for many years, as will consulting. McKinsey/Bain hire a lot of Oxbridge PPEs. Make sure you get a job with a route open to a Global HQ. Being no 1 in a "we don't care about that market" subsidiary is frustrating.
Avoid becoming Audit fodder at a beancounters. They are good at spin about their jobs, but............
After a year or two of employment, if that is what you decide to do, then consider doing an MBA at a decent School. London, Manchester, Insead still have good reputations in Europe, and a pitch for Harvard, Wharton, Stanford and Columbia is always worth it.
But..........................I went to Uni and PG to have fun. Much of the rest of my career was kind of accidental, and I enjoyed most of it - including lots of Gold years. (When Gold meant GGL).