For me, I find it very easy to just forget about school and not do the work, then i'll go back and regret not keeping up to speed with everything that needs doing. I will then become very overwhelmed with the workload & it's actually really unhealthy for me.
Through the holidays, try your hardest to do a small bit of revision every other day, perhaps in the hour after meals when you're letting your food go down and don't have anything to do, you don't necessarily have to revise / work for a full hour, it can be for 15/30 minutes, but it's good to be doing something school work related in the holidays, especially longer ones like summer and Christmas. If you are working a job and find that you're lacking in motivation to go if it's a weekend job and you're not doing anything all week, try and do some chores every day to keep you motivated to do something. Other ways to maintain work ethic if in a way you haven't got any studying to do, you could write in a journal or read a book, this keeps your mind active and can also increase your vocabulary which is great for english!! To some degree, gaming is also good for keeping the mind active and keeping you focused, over doing it, perhaps not so much, but it is certainly effective in some respects! Finally, maintaining your school sleeping pattern is very useful- sleep is difficult for many people and I won't delve into that too much as it's a different topic, but I do understand sleeping is hard. But maintaining that same sleeping pattern through holidays as much as you can, will keep your brain trained and focused and won't cause you to be too tired during the holidays!
Hope you all have great holidays & last months of school!!