you book out your own darkroom, with an enlarger, processor, trays etc. it means you're a lot more productive as you can turn the lights on when you want, change developer when you want, etc.
I'm sure if you ring up Keith will do you a deal on a first/introductory session!
What do you mean by private? You’ve got to book the whole space? Checked price and it gets pricey to book for any decent length of time