It was quite stressful with trying to keep an eye on the 2 year old because he wanted to play with the big boys but we only ever went to the main stage, and parked ourselves at the same spot (to the left of the main lawn) so that the DS could play in front of us but out of range of the speakers.
We also did long afternoon naps and then went back around 6-7pm to see the evening show.
I brought lots of glo-bracelets on advice from here, and covered the DS in them so I could spot them at night.
I hope the weather is better for you than for us although we had a brilliant time anyway.
If you are in a group it will be fine, as long as you share the childcare - DH and I took turns taking the DS to child-friendly things in the morning/over lunchtime.
This will be our 7th year jamais! Just really worried about how wet the last few years have been and ds isn't quite walking yet. Not looking forward to him crawling through the mud. he just wants to go and explore everywhere, so one of us will spend a lot of time following him around and the other will be doing a lot of craft with dd.
Have you got those all in one suits (or waterproof dungarees)? I think the dungarees are better because sometimes it's hot and rainy iyswim, so they can be in a t-shirt but with the waterproof trousers on.
That far left hand side (as you look at the main stage) is good because there are hedges all around and he can crawl up to them but can't get to far iirc.