I often have to go to York on Saturday, and my big advice is to keep moving. You don't have time to sit and smell the roses. While the meet is 5 hours, people are packing up in large amounts by 12. That being said, if you move like I do, scanning each table quickly, you can make it through in 3 hours (that's me being 25 and working in a profession where I have to scan the crowd/documents quickly and pick out details).
That being said, Saturday is a great day for deals!