I know summer is a time to have fun, but it's not great doing nothing in bed. So I would like to know if you think it's okay to start preparing for 5th year during summer, as it keeps you occupied and active-minded (sport and meeting up with friends works the same way), or if you think that would be "goody-goody".
I'm not sure if you could or not. Unless you have notes and stuff for the syllabus of your subjects. The Leaving Certificate consists of a lot more work and the courses are more broad than Junior Certificate. Here's what I would do. Look up the syllabus online for each subject you are going to take and ensure you are familiar with it. Look up with you are confused on. Try to find some Leaving Certificate notes and read through a few of 'em. It's great that you want to work through the Summer but ensure not to work too hard! :)
I'm gonna do a bit of work too but not a lot... Just enough to keep me from being bored between work and meeting friends!
Give your head a rest for a while your brain will become saturated and won't be able to learn as much as you would like . My advice would escape with your family for a few days maybe and relax ! :) Good luck anyways next year though enjoy the summer and don't work too hard :)