Be aware the Hall opens at 2pm & seating is unreserved. There is a silly mad rush at 2pm (even a starting line/tape!) for pax to rush & reserve their seats....if you don't want to sit on the grass....you know what you need to do.
I didn't find it too bad for his first gig there (couldn't make the second). There were a few people there early to bag the best seats, probably less than a hundred, but we rolled up about half an hour after the place opened, got front row in the centre easily, reserved the seats (well, put our coats on them anyway) and wandered off to look around the hall. Maybe it was worse for his second visit? The seating is quite steeply raked and gives a decent view as long as you're fairly central and not too far back. Might try the grassed area in front of the stage this time anyway as long as the weather is okay.