We went to GWL for several years running, and loved it. We arrived at 9 a.m. just as it was opening and stayed till it closed. We took a packed lunch and had a wonderful time. You can buy as you go around, putting things in the 'creche' , and collecting larger things afterwards.
I stopped going when it got combined with the Good Food Show, it was then too big and too many people for me, but that is a personal response only.
It is very easy to buy more than you can use, but once in a while that is fun! Take plenty of water or whatever you like to drink as it gets very hot, even on wet days. It takes us about 2 hours to get there, but always wanted to come home as sleeping in my own bed outweighed anything else, and we didn't have to try and keep plants and things happy in the car overnight, then load and unload them when tired the next day. I was usually washed up for a day or two afterwards, but it was worth it.
Now I am a good few years older I tend to give it a miss, I may try Malvern again this year. that's a great show too.