I think the oak lodges will be newer, but perhaps not in the most established plots as the pine lodges probably are. If in doubt phone or email reservations, they are more than accommodating and helpful.
It would be great for a 4 year old, but bear in mind you will be going at a very busy time with lots of older children there.
There are some lovely walks, outdoor playgrounds and a small soft play place supposedly for under 5s, but the older children try and get in and I have had to complain on more than one occasion as the older children had been playing tag in there among the babies and toddlers trying to play. They really ought to introduce some kind of key card system on the door.
There is also a swimming pool which has two toddler pool sections.
During the holidays they will probably have some activities, for a 4 year old this will probably including some sticking/colouring activities and maybe playdough/beading.
There is a bistro to eat in, or grab coffee and snacks in. A spar shop, laundrette, pub, beauty salon, bike hire, gym and a gift shop with various leaflets of what to do in the area. You an get Tesco to deliver there, but the Spar shop is quite well stocked.
It is not holiday campy at all, it's more like a tiny version of centre parcs.