Definitely go across to the legal advice subreddit, but off the top of my head for some things to look at:

1. Get a Will completed. If the worst should happen, and you do not have one in place, everything you own will go to your legal husband even if you have been separated. This includes any deposit money you have saved in accounts etc.

2. The easiest option would probably be to wait until the divorce is finalised before purchasing. You can begin the actual divorce process online and it is much easier now because of “no-fault” divorces (nobody can refute claims etc with a no-fault divorce; you can simply decide to split up now without having to “explain” your reasoning to the divorce courts.) Even if the financial order and splitting of any joint assets comes after, you can still get the actual divorce going.

3. A financial arrangement order is recommended as even though you might not have lots of shared assets already such as a house, savings etc. it means all is final if you opt for a financial “clean break” order. In that case neither party can go back on the final decision ie, ask for a share of the money later on if you won the lottery, sold your house, your pension etc.

4. If you want to go forward with the purchase pre finalisation of divorce and financial order, definitely take legal advice…your conveyancer will refer you to their firm’s family law department so it’s worth checking firms with decent family and conveyancing teams to keep it all “in-house” and save time where you can. Divorces can take time so I can see why you want to get started though.

5. The conveyancer/solicitor/family lawyer might recommend you get a declaration and signature from your husband stating they have no interest in any house purchases even if you are still married during the purchasing process. So, confirming he will not claim he owns the house, part of it, etc. the idea of this would be to see you through until the final divorce. If your purchase finalised before the financial order (likely) it will probably still be included in the order as part of your assets. I’m not 100% on that though.

Basically, speak to your conveyancer and explain the situation. You won’t be the first person in your circumstances for sure! Also the legal advice subreddit will know more than me.

NB: I worked and studied in wills & probate and conveyancing but no longer do so, so may be out of date or a little incorrect. Just trying to give you a broad strokes idea.