From experience, can anyone tell me what capacity rucksack is required for an autumn event. I realise that it obviously has to be big enough to fit in the kit you have, but since i've yet to buy the tent and sleeping bag i'd also welcome advice on the selection of those articles also. I have got in mind the biggest Camelbak with 35 litres capacity.

Depends how comfortable or not you want to be, and whether you are doing it solo or not.

I've got the TN Solar Tent, its fairly popular though the lightest are the single skin Sup Air and new Polaris tents. Not sure how either would be for general use though.

Rucksack, IMHO Camelback's are over priced
I'd recommend the KIMM 35ltr rucksack, its v.light, handy pockets on the hip belt & has a pouch for a hydration system.

That said I also had a single small pannier and competed as part of pair. Plenty carried more gear, plenty less.

Sleeping bag, I'd definitely recommend a Down bag over Synthetic which are heavier and more bulky.

Kimm sack 30 -35 ltr definitely!!

Actually a team entry. Would like to be comfy, but for one night I suppose that as long as we're dry we'll be ok. The pannier idea is great but i've got a full susser with a rear swing arm which prevents proper panniers from being fitted, although a seatpost rack is another option. On the subject of the TN solar tent, how much?

Team entry, that's sensible!

From memory TN Solar should be available at �199. There are some cheaper imitations, Vango do something similar at just over �100.

Seat post mounted pannier rack should be ok. Many simply fit a waterproof Ortlieb stuff sack to it.

does anyone know where i can get a KIMM AR35 from?

Could try the KIMM website (KIMM.com), I believe they had a deal with Field & Trek regarding gear for the event.
Don't you know where you live, but bought mine from CCC Outdoors in Sheffield a couple of yrs ago

Lowe alpine do some very good 35 and 40 litre rucksacks. The 40 litre one is a bit older in terms of design but is still brilliant. It has good side compression straps, so if your kit doesn't quite fill the bag you can compress it along it's entire length. Some sacs don't have this and result in everything sinking to the bottom.
If you have lightweight kit then the 35 litre sac is even better.

Cheapest place I have found them is Gaynors;
http://www.gaynors.co.uk

not sure how local to the event they are, but they are up in cumbria.

Agree with the Lowe Alpine comments - try their light weight climbing sacks though, rather than the so-called event sacks. They are lighter, tougher, still have compression straps, but don't have silly dangling straps and webs that just get snagged.

Also the climbing sacks fit more closely into your back (better harnesses) and don't have pointless zipped closures that mean you can't load them easily.