Hmm, I publish this public because my answer got bit out of hand and some of the followers might also have something relevant to say, since this is in general super difficult question…I also recently posted some work vs. school discussions in this blog, if it’s any help.
All of those degrees are so different depending on each country, so it might be hard for me to say…for example, in Finland you can’t even study illustration separately, you’re either self-taught or take courses in graphic design because it’s useful for figuring the print process. Personally what I got best out of graphic design studies was honing my eye for details, questioning everything and conceptual thinking. Not so much of the technical art skills. Best kind of school would be where you feel like you could get as much (or more) out of your fellow students as you get from teachers. Good thing about graphic design for me was that everybody in my class was really doing their own thing and ambitious about it, I learned about motion graphics, film, fine art, photography, illustration, comics; a real mish mash of everything visual there. Although it’s really a double-edged sword, on the other hand you can develop to become really versatile, but then again I really fear sometimes I’m not good enough at anything specifically, which is what you end up doing in worklife anyway.
What I’ve learned at work is the animation art is really different from illustration and graphic design has hardly anything to do with it (well, it’s a large umbrella!). Moving images are really different from static ones and with my style it’s sometimes a struggle to be conscious where the attention should be, rather than just making everything look “interesting” which in animation means you can’t focus anywhere, even if it was a nice picture. I also paint a lot in here: sure, I have painted before, but more as a part of illustration and whenever I’ve felt like it, so I hope I’ve become better at understanding light and color here. So technically I’ve learned more about painting and animation at work, but in different aspects I did learn lot more at school.
In the countries like US, I understand the pressure what comes to picking the art schools since it sounds hella expensive. In Finland no matter what degree you take, you can deal with student loan and such quite easily compared to tens of thousands of debt. That way I didn’t feel too anxious about what to study. Then again, in which US school you’ve gone to probably matters more in CV, and the connections you make there. Connections are important everywhere.
In short what you get from art school at the best would be fellow students, trying out things you can’t do in work and getting connected somehow. What you learn at work, is probably so different for everyone, but it will be harsh reality of deadlines, solid executions and learning fast or falling behind. So maybe just for getting some base for thoughts, idealism, critique, your own expression and trying out things, school is great thing to have, before getting tangled in work. You have time to get valuable things out of both.
Maybe some followers can recommend some schools in UK? Because really I think you clearly have a knack for illustration/graphic design, but it’s all up to what you think would be most fun to learn about right now!