Chronology- ages, date of marriage, age of kids
children- your wishes for where they live and contact. Depending on ages, who main child carer now . If children are older then what you think they may want.
Finances- house value, mortgage outstanding, any other property with a value of over £5000 say, all your bank accounts, policies, your debts, your income, your outgoings, your pension and transfer value. Any financial details you know about your husband (don’t endanger yourself by trying to find out things behind his back).
Solicitor will give you an overview of the situation. You may need to serve divorce proceedings on him and then sit out the process in the same house which is something many ladies in this forum have done. The solicitor can give you advice on what is likely to happen.
Good luck