A few observations.
Prospective commercial pilots would be well advised to take the deep view on this. If you are asking the question "what do airlines want" then that is only part of the big picture. "What will help me succeed at an ATPL" is better, "What will help me succeed over my entire career" is better still.
It is certainly posible to get through an ATPL with almost no education at all, however you need to ask yourself do you want a huge struggle, loads of rote learning yet only a shallow grasp of theoretical side of things? (never mind the concepts, just question spot?). If you struggle with Physics to AS level, you are going to have a struggle with the ATPL theory. If you are dropping physics now, all you are doing is postponing the need to understand it.
My basis for saying this: Previous ATPL ground instructor, previous airline pilot, current teacher of Physics.
With regards to degree courses. Thats a tricky one, but here a few thoughts:
1. The training scene only ever gets more convoluted and more expensive as yet another training requirement is successfully handed off from the airlines to the prospective employees and the regulatory authorites do more arse covering. Therefore there is a strong arguement to train NOW, or a soon as is possible.
2. Don't do a degree for the sake of doing one. Its got to be something you are interested in and can do well at. A few specifics: Some folks in this thread have mentioned engineering.
Do not do Aero Eng, (or any form of engineering for that matter) unless you have rock solid maths and Physics to A2 level. If you can't do them to A2 level and score top grades then don't do engineering. In fact I'd go a step further. If you want to do Eng, I recommend doing Double Maths to A2. If you find it all pretty obvious, then maybe an engineering course is for you. Engineering is hugely maths reliant. This can not be overstated!
3. A degree imho is unlikely to be decisive in getting a flight crew job, so you have to ask whether it is worth the time and debt you will incur. You may curse those three years later in your career when the airlines enter a slow period and don't recruit, or people with Dates of joining 3 years earlier than you get their commands 10 years before you as the airlines expansion slows down, etc, etc.
4. But a degree offers other possibilities, both within the industry and without. In my case a degree in electronic eng helped me get into the training department of my first airline within about 10 months of joining. It allowed me to earn good money during the early 90s recession, and it gave me a get out from flying when I realised that half a career as flight crew was enough.
Now you all are probably fixated on flying for a living, and think that will never change.
Some of you will need to be levered out of the flight deck on your 55/60/65th brithday, but many will leave, or wish to leave, before then. You'll want some options.
When I left BA, a very small number of people expressed disbelief, but a far greater number expressed the desire to have skill set that would allow them to do the same and still retain a decent income.
If you are thinking "I will fly aircraft forever" you are failing to have a suitable mindset as a comercial pilot. After all, we always consider the need for an alternate, don't we
pb