tax credits - getting married but not living together yet. what to tell hmrc

Hello
I am hoping someone could give me some guidance here. typically my situation isn't straight forward.

My partner and I live separately. Me with my children, him with his parents. He is in the process of purchasing a family home for us all and anticipated all this would be completed by last month, we are due to marry in a few weeks.

As it stands I claim some tax credits for my household, he does not. It is looking like when we marry the house purchase will still not be complete. So for the first few weeks we will continue to live apart.

He cannot move in with us as I have 3 children 2 of whom share my room and my eldest has their own room. If he moved in he would be sharing a room with me and the 2 youngest. Although he will be their step father I do not feel it appropriate for him to share a room with them. We cannot move into his parents home due to space.

So, I realise I need to tell HRMC when we marry as it is a change of circumstance but will my tax credits stop? My tax credits pay for nursery etc so I cannot work without them whilst I am still the only earning adult in the household. When we live together we will no longer claim tax credits as we will be able to manage without them due to combined incomes and only 1 house to keep

sorry for the ramble but I feel it is better to explain in full and give clarity

Thanks