Hello,
I am somewhat older (early 40's) and perhaps in the job you so desire (long-haul widebody Captain). My advice to you if I may take a few moments of your time. Go with the Accountancy degree and always have that to fall back on at any stage in your life should you need it. You may never want to fly all your life and even maybe you might not remain medically fit to fly, so then you have another skill you could make a good living from.
Flying is a wonderful career and a reasonable living can be made from it. But the true flying is in an abbreviated story I will try to tell in as quick a way as I can.
Imagine the ppl pilot in his Cessna who see's the Seneca pilot coming into land and wishes for that next best more powerful aircraft to get his hands on. The Seneca pilot saw a King Air only an hour before and wished he could be flying that. The King Air saw the...F27 who saw the 737 who saw the 747 take-off at a large international airport and wished to one day to fly the 747. During the long-haul 747 flight through the night, the 747 crew saw the Space Shuttle zoom by overhead in space and thought that must be the ultimate flying job. Unbeknown to the 747 crew of course, a shuttle pilot was looking through a powerful telescope to earth and saw the ppl Cessna and thought, one day I will give all this up and get back to real flying and fly that Cessna again.
So the story is there to make us understand that no matter what you do it will never be the right thing, even in flying and I too would love to get back to fly around casually in that Cessna too. Unfortunately, I have to endure those many long hours awake through the night, bleary eyed and stuck in the aluminium tube because I have no other profession to fall back on. I now would never want to give up my love for flying, but I wish I had another career to fall back onto should I so choose. Then I could sleep in my own bed at night and fly for fun at the week-ends.
Those of us who fly have it in our blood, it's a desire that has to be fulfilled, but be a wise man and keep all your options open by getting your degree or I am sure you will always regret not having that back-up option which is there for you now.
Best of luck and remember, commercial pilot or private, you will be flying and your desire to fly will be fulfilled. Automation today has taken away the role of piloting and the autopilot is in control for all but the first and last 500 feet of the flight. The glamor days of flying has passed us by and modern aviation has become a tiresome challenge of rapid turn arounds in the low cost market or short lay overs and fatigue on long-haul. Should you get into commercial aviation in the future and realize my advice has come true and you wish to change back to Accountancy, be glad you did your degree.
Good luck.