I'm going into year 13 this year, I do graphic design A level, and did Graphics GCSE. As pretty much everyone here has said, keeping on top of the workload is important, I do quite a lot of work outside of lessons. That said, the workload isn't particularly more than GCSE, and I do four A levels and am managing it fine so far. Transitioning from art to graphics isnt that big a deal, in my class (8 people) only two or three have done graphics at GCSE. Learning to use the programs is way easier than learning to draw/paint/transitioning from graphics to art. If you are struggling with workload or a project then remember that one upside of art subjects is that they are very sociable - even if the projects are individual, talk to your classmates and figure out an idea of what people are doing or how far along they are. Especially talk to people who have done graphics before if you need advice on how to use programs like illustrator or photoshop - theyre pretty easy to pick up but only if you have stuff explained to you. Alternatively, anything you could ever want to know how to do on adobe is on google or youtube. Also talk to your teachers - they like graphics and like teaching people, so if you ask for help theyll help, thats their job.
If you want references, use pinterest (and you do want references, or your work will look crap- i cannot stress this enough, references are really important). Sketch everything before you start on a computer, its way easier to get ideas (doesn't matter if they look crap, I can't draw for ****). Most of my work is digital, but that's mostly bc I can't draw or paint. Most of graphics is done on either illustrator, photoshop or indesign, which are all adobe programs. They're really great programs and easy to pick up (the company itself is an absolute ******* but dw about that). We did a project on printing, and i did loads of screen printing that i really enjoyed. We also did a project where we made 3d models and took photographs and added text digitally which was really fun. Generally graphics is digital, but it doesn't have to be - talk to your teachers, ask if you can scan in drawings and use them. As an art student you're actually probably at an advantage to be honest. Play to your strengths sometimes, but remember that a lot of your projects won't necessarily affect your grade, and that its important to experiment and learn new skills. Our projects are all submitted as powerpoints bc its easier than making physical portfolios.
On stayin sane - listen to music, even if it slows you down a bit itll probably make you happier while you work which is way more important. Don't work for more than an hour at a time without a break. Take a short walk, get some fresh air. Look up stretches to do for carpal tunnel as well, stretch your wrists out and they'll feel better. Remember to drink water and eat stuff, if your energy is down you'll be way less creative and get rlly tired/cranky. Don't work through lunch and break, go talk to your friends and eat - taking a proper break is way more beneficial than getting an extra 20 mins work in. Also get used to the fact that six months in the future, you'll probably hate what you just made. That's fine, it just means that you've gotten better.
Chances are, even if you love graphics there will be some projects that are just boring or you don't like. You can try and counteract this, mainly by making sure that you don't waste time on outcomes you hate. Sometimes its way faster to abandon an outcome and start again than trying to salvage it. Make sure you use multiple references that you really like, and steal ideas from them. DON'T only use one reference, or it'll look really similar. Use at least three or four. Literally all graphic designers use references - even at professional levels. If you don't then your work looks bad.
I really love graphics, and I like doing little projects that my teachers haven't told me to do. It means that I have a bit more freedom, there's no pressure to finish it, and it means i can practice using programs and learn new stuff (google spoon graphics - its a blog that posts free tutorials for illustrator and photoshop, the neon sign effect is a personal favourite). It also gets you a few brownie points with your teachers, and means that if you need a little break from a project you can still be doing something useful.
Memorise shortcuts for tasks, itll speed you up loads more than using the mouse to click on everything. If you need to type something, don't use the standard fonts - look on dafont.com or myfonts.com for cool fonts. If you can't download fonts bc its on school computers, then use the snipping tool to copy a snapshot of the preview over to illustrator, and then use image trace tool to turn it into a vector. (Google image trace if you don't know how to do that).
Art subjects pretty much naturally attract students that are less traditionally academic, and the teachers are usually the same. the art department at my school are absolute ****ing banter, and are really chill, but they know their stuff. Talk to them if you need to or if you're worried about anything. And talk to your classmates, if you feel like you're getting behind everyone else might be in the same place.
I didn't do art, so idk how different the two are, but im pretty sure theyre quite similar. Its assessed mostly through coursework, with one massive endpoint exam (15 hours on my course). The main difference between graphics GCSE and A level is that all the annoying people who chose it as a doss subject have left.
Sorry if thats really long and rambling - hope it helps. TL;DR - its not a doss subject by any means, but no A levels are. Keep on top of your workload, talk to your teachers, USE REFERENCES and take breaks.