5 hours of driving is quite a lot! It depends on what you are going for or what you want to see really. It's the biggest show in Scotland, so you will see more chickens in one place than you've ever seen before, and it's a great chance to meet people. However, as people drift around, it's also difficult to sometimes find someone you want to speak to.
I would think about when you want to go. Judging is done on Saturday, and that means you can't always look at all the birds, if the judge is still in that aisle. But equally, they box up the birds starting about 2pm on Sunday, so if you want to go on Sunday, it would have to be morning. Saturday, it might be better to go late morning, and hopefully you'll get to see most of the birds in the afternoon.
The selling pens will be open the whole time, take boxes with you if you think you might buy something. Prices can be high, as they tend to be show quality birds.