A lot of areas have got support groups etc, but when you are awaiting diagnosis, it is not really on your mind that this is the place to go... you don't want to be jumping the gun. Afterall, there is still hope.
Though, you're network of "friends" that you have built up since having your child(ren) seem to soon stop calling, emailing, asking you to meet up once they have either heard your news and made false assumptions or witnessed a meltdown or poor behaviour for themselves and don't want their children to be mixing with your child. It may sound harsh, and you may think that you'd never be like that, but it is almost certain that you will encounter this at some stage.
There are places and sites out there that can really help you feel part of a community, group or family and offer you support, before, during and after diagnosis. A lot of the parents that you do manage to speak to may live quite a long way from you, and you might never get to meet, but thanks to this technology age that we do live in, it is quite possible to still form a relationship - albeit a virtual one.
I have come across some new friends, who all live a long way, some even in the USA. We are there for each other and instantly have a bond that not a lot of other people have - loving someone with autism. It is great to hear how they are going on, their highs and lows, their expectations and despair. It's nice to hear them have good news and know that even though every minute of living this life is hard work, it is all worth it. It is inspiring to know that it is possible and that you are not alone.
By far the best site is http://www.netmums.com/ on the forum and into the special needs and disabilities section. You can ask for support, offer support, get great tips and give out great tips. Or you can just join in and share experiences and start talking to others. Once you see someone that you think is "on your wavelength" it is quite a simple step of clicking their name and sending them a private message.
You can also meet local mums, not specifically parents to autistic or other SN children, but local nonetheless. UK site.
http://www.experienceproject.com/ is another good one, the site is a bit in your face and difficult to get to grips with, but you'll be inundated with responses and comments to your stories. This is also not just SN related, if you are having any other problems too, or have a favourite activity or sports team, you can make new friendships there too.
http://www.cafemom.com/ again is great to develop friendships, in your journal you can post that you wish to meet other parents in a similar situation to yourself and then you will get responses.
And of course: Facebook! The amount of groups within facebook is actually quite astounding and it's a great and easy way to share everything that has been going on, fast to get responses when you are looking for help or needing to sound off during a particularly bad moment - or just after.
A lot of the American sites are pretty good for you to get quick responses and support. Fair enough, if you live out of reach of one another, a virtual friendship is probably as far as it will ever go; but when you are stuck in the house and your little one has gone off to bed, or when you are having a bad day and just need to rant to someone who "gets it" then isn't this the perfect sort of relationship?