I think with sleep school if you call them crying that you are a single mum and that you are desperate and that you may do something irrational if you don't get help soon they may be able to get you in earlier (but you didn't hear that from me...).

If you can't get in earlier I think it is best to get DP out of the way and really focus on the issue. The change of routine and bedroom thing to start all over again from scratch and implement a new program as PurpleMumma suggested might do the trick.