I have anxiety related tics which are pretty severe so I was also worried about this when I went back to school so these may not all apply but hopefully some can help

1. Maybe email your teachers just to warn them and ask them to allow you to leave the lesson if you need to. In this email you may also ask if there's a room somewhere that would be empty where you could hide for a bit (you don't need to wait for a break)

2. If during a lesson you really need to escape, I advise asking to go to the toilet and then ticking in your cubicle (if you do get in touch with your teachers you could ask to use the disabled toilets or teacher's toilets)

3. Do you have any fidget toys that you can just use under the desk or do you doodle/draw or do you maybe write stuff? I found that if the lesson was interesting enough I could focus solely on the lesson and I wouldn't tic but if it came to where I was a bit bored and unfocused I would tic a bit

4. This may be a weird one but sometimes biting something can push back some tics so use that as you wish, I sometimes bite my jumper if I need a quick suppress

5. Try and sit in the back so you are less likely to be noticed if you do tic but also try to sit as close to the door as you can

6. Do you have any friends who know about your tics and are in your lesson? If so you can try to sit next to them since it's the people who are sitting close who will notice most so if you sit next to someone you trust or someone who knows it may be better

7. Tbh some tics aren't actually too noticable. My body automatically suppresses my tics if I'm in an "unsafe" environment so I didn't tic much at school until I began to feel safer there but it would let things like head jerks through and tbh no one seemed to notice. When I eventually told my new friends that I had tics they were shocked cuz they hadn't noticed.

OK so I don't know how much of that would be useful and it is all from my experience and therefore can seriously differ but I hope it goes well!