MY name is Clare
I shall do my best to hep you - I have reviewed your other thread.
For clarity if your were married, rather than in a Civil Partnership - then you apply for a divorce NOT a dissolution.
You can issue a Petition based on her Unreasonable Behaviour immediately - even while you are in the same house - you just need to make sure that you progress it promptly.
Once the Petition is issued you can start dealing with the financial issues - you will NOT still be there in the same house when the child is 18!
Please ask if you need further details