Thank for that, just rang him & they're closing (or have closed) down, he gave me the phone number of a wonderful woman in Wentworth who talked to me for 1/4 hour & gave some great advice about what to look for & what to do.
Turns out it's probably OK, they apparently hop around on the ground for a good few days with the parents coming back & feeding it every now & then while they're learning how to feed themselves & fly. It looked confused to me, but that was probably it wondering what that freaky evolved monkey was doing staring at it, I couldn't get within about 30ft of it without it hopping & if it was distressed then chances are it'd let me get closer & pick it up. I'm going to go leave a bowl of water out somewhere obvious for it (as it's hot that's about the best thing I can do apparently).
If anyone has any similar questions or needs advice you could do a lot worse that calling [number removed by request]. They're very full at the moment though due to the place in Woodseats closing... Lots of very parroty noises in the background too...
**edit - phone number removed. They're overbooked, rushed off their feet, & generally harassed. The rook had got very poorly looking over the course of the morning with no shade to hide in, & hadn't touched the water I'd put out. She sent her husband to come & pick it up, it'll be in their aviary, hopefully eating & drinking by now, at the very least it'll be in the shade. She wasn't too pleased that the guy in Woodseats ONLY gave me her number, as he apparently knows very well how over-capacity they are (sounds like they took a lot off of him).