It's best to go and look round a few and get your name on the list. Zoom has a good reputation but a long waiting list. I am also looking at Headstart (my DS will start at nursery next year, so I can't really give any first hand experience of what they're like). Some of the waiting lists are very long, I wish I'd thought to look into it when I was still pregnant!
Agree with schmalex - look around as many as you can. I'm in same area as you and was also shocked to see the waiting list. Having said that, we paid to put DD on the list for three nurseries, about five months in advance and despite being warned about the number of people ahead of us in the queue, we were offered a place at all three. To be fair, it prob helped she was starting end Sep/beginning Oct as the older kids started school then. People put there names down but don't take the place up for many reasons - change of mind, wanting to be sahm or, like us, taking up places elsewhere. If it helps, we also went with zoom (different branch) and are very happy so far, as is DD. Good luck!