I've fallen behind on research and thinking about this due to being ill the past few days, sorry.
I'm still leaning towards the barn for some reason. But Lal's Thorpe Farm Bunkhouses and Clumber Park have me second guessing. Which isn't good at this stage in decision making.
Let's make a list of criteria and see which ones fit the most the best;
Capacity
Proximity to railway
Proximity to bus stops
Proximity to fun stuff