You can take camping chairs Paul. There are 3 entrances to Oulton Park, 2 take you to the outside of the circuit and the main one takes you to the inside (have a look on their web site and/or Google earth.
Parking at these big events is organised so it's pot luck where you get parked. You can access both inside and outside of the circuit via 2 bridges, one at the start/finish straight and one at the other side of the circuit at Clay Hill. There are also crossing points across the track but I'm not sure if they open these during big meets.
There are grandstands (yeh, right LOL) at Lodge and Old Hall, £10 extra.
If you are able bodied try to get there early and have a wonder round, almost all of the track provides good viewing.
Druids is a bit of a trek to get to and Knickerbrook has chainlink fencing.
My fav spots are on the inside at the exit of Lodge and Old Hall, these are quite often where the incidents happen, Old Hall being the first corner.
Photography is good apart from the mentioned chainlink fences, most of the rest of the circuit is devoid of such things.
Weather's looking reasonable and if you get bored with the racing you can always spot the light aircraft flying over from/to Liverpool ;-)
Hope you enjoy the day if you do come.
If you haven't been before it's a quite picturesque circuit and interesting to drive.
No access to pit lane but paddock is open and on the inside of the circuit next to the main entrance.