I'm afraid I don't have any financial advice to offer, but early intervention is best thing working in your favour right now. It really is like the saying goes, "It's hard to see a silver lining when you're stuck in the stormcloud". How true of ASD.
For your own download and respite, perhaps start a journal/blog, maybe share it with your partner. Tell it everything, allow yourself be un-judged.
For managing at home before services begin etc, equip yourself with basic activities, strategies & simple routines that will be useful throughout the day regarding all the kids. Maybe create a visual timetable for you, and the kids, to follow.
You're probably already doing these things I've suggested, but my main point is to see your own strength and use it to push forward.