Anna - if you lo is going to school Sept 2009, then don't worry. You can't really go on a waiting list as they don't exist until after places are allocated for the year. If you need a school place for this Sept, then you may have a problem as the good schools are always oversubscribed. Hwr, without an address, you can't go on the waiting list for this year yet, so you need to get a house - they will check you have a local address!
I second the thumbs up for the Children's Information Service. They are good - and you will want to search for childcare in Brighton and Hove except East Brighton.
As for recommendations, in the Fiveways area I would recommend Fiveways pre-school - it does morning and afternoon sessions and lunch, so you can just do 2 1/2 hrs, or a whole school day iykwim. Also, Joyland is a good pre-school, and it has a sister nursery for full daycare which is called Strawberry Hill, which is also fab. These are both sort of feeders for Balfour and Downs Infants schools which are excellent.
I could name loads more in other areas if you want...
I also second the vote for the Booth museum - always good for an hour's distraction, and across the road form a park with sea views and a cafe!
You really need to come and wander around and see which areas you like. Brighton has so many different places, you need to see for yourself. We can then get more specific