We rally with the C&CC but rally fields are usually the same no matter what club you belong to.
Rallies normally start on Fridays and close on Sundays, check with your local section to find out what the starting time is because sometimes there are reasons ( when rallies are on school playing fields for example) why a rally cannot start before a given time and it's not the done thing to arrive before the rally steward has had time to prepare the site for your arrival.
A fully charged leisure battery should last the weekend during the lighter summer months if you are just using it for lighting, the water pump, radio etc so the lack of mains is not a problem.
Often rallies are close to attractions such as rivers, pretty villages, pubs etc so unless you are a tv addict a weekend without the 'idiot lantern' makes a pleasant change.
Rally fields vary, some are held on or near to normal caravan sites with ehu, wash blocks etc but most are held in fields ( often on farms) where the minimum that will be provided will be a drinking water tap and a chemical loo dispersal point which can, in some cases, be a manhole.
The form is never under any circumstances take any part of your toilet to the drinking water tap 'to wash it out', use a watering can which can be used to fill up the flush tank and also to collect the water to wash out the storage cassette.
Grey waste water can be emptied along the bottom of hedges etc, the rally steward or any of those present will be happy to fill you in on any details that you are unsure about and to show you where the drinking water, loo emptying etc is.
Rather than use the caravan system for drinking water we keep some plastic bottles to fill for drinking water, hot beverages etc and some ralliers use filter jugs as well (we don't).
Make sure that you have enough lpg, the stove, hot water and most importantly the fridge will be run using lpg so you wouldn't want to run out of gas. Check that both systems work on gas before setting off.
Levelling blocks are a good addition to your 'rally kit' as are some house brick sized wooden blocks to place under corner steadies and jockey wheels. Some rally fields are reasonably level but many can be on slightly uneven or sloping ground which is no problem if the view from your caravan windows is a slope down to a picturesque river bank which 'full facility' caravanners would never get to see and you've got the kit to level up.
Use a good quality toilet chemical, obviously your toilet is used to it's full potential and toilet roll such as Tesco or Asda own brand dissolve fairly easily, avoid the quilted stuff which doesn't. (we don't bother with the over expensive 'caravan' toilet paper'.
We still have hot water for on board showers, if your caravan hasn't got an onboard tank a spare Aquaroll can come in handy to prevent you from running out of water mid shower. Don't leave the shower running, shower, turn off and soap then turn on and rinse.
There is a common misconseption that if you take part in rallies the steward orders people about, insists on inch perfect straight lines of caravans and you are forced to take part in organised activities.
All of this is total rubbish, obviously on well attended meets the steward will want to maximise the pitch availability whilst keeping the correct distance between units for safety and privacy, if activities of any sort take place you can either join in if you want to or do your own thing.
You will get to know the people on the rallies if you give it a fair try and go on a few, we've often sat outside on warm summer evenings chatting and joking over a few drinks with our fellow ralliers, it beats watching tv anytime.
We've also learned from rally goers, they are happy to pass on tips and ideas and will tell you which rallies are held at the best places and we use our caravan as often as possible, to it's maximum potential and without breaking the bank.