I'm trying to add my school timetable to google calendar but the weekly repeating options don't account for there being no lessons in between terms. I also haven't found a way to delete multiple events at once (i.e. lessons in the holidays)
You are correct, you cannot automatically specify "skip dates" when scheduling a repeating event. You have to manually delete the events scheduled between terms (be sure to select "This event" when prompted about deleting recurring events).
The fastest way to delete multiple events at once is to use the "Schedule" view, or search for your event title. Then click on each event you want to delete. Google calendar Keyboard Shortcuts can be a time saver too.