Most roads are 30 anyway, but I see what you mean about it being quite 'main'.
We live on a pretty busy road. It's not what I'd ideally have chosen but we have the compromise of a river view, park and swings over the road and a gorgeous house DH and I fell in love with.
It's fine. We have a safety gate in our hallway that blocks off both the stairs and the front door so that there's no danger of either DS or the dog darting out of the door.
Parking isn't really an issue, occasionally DH has to park a bit down the road, my car goes on the drive, but it's never a case of no space at all.
Not particularly noisy most of the time, or at important times like night time anyway, and we don't even have double glazing. We get quite a few lorries, tractors, police cars etc but they all tend to be during the day anyway.
DS's room is right at the back of the house away from the noise in any case. He absolutely loves seeing all the tractors and other exciting things going past.
At some point I'd like to be somewhere where he can go outside and play, but that's not going to be a problem for a while anyway.