You would be insane singularly ill-advised to embark on mediation without knowing what you are legally entitled to expect in respect of the division of property/savings/pensions/childcare arrangments etc on divorce and you could easily become disadvantaged if your h lawyers up and attempts to pull the wool over your eyes by spouting a load of 'legalese' that favours him.
Source recommendations from friends/colleagues or find your nearest Women's Aid service here www.womensaid.org.uk/domestic-abuse-directory/ and ask for a list of solicitors in your area who specialise in divorce and family law and, as springy has said, have specific expertise in cases of domestic abuse/coercive control.
Don't hesitate to take advantage of free initial consulations with a number of solicitors as it's important to find a lawyer you 'gel' with and have confidence in their ability to be ruthless proactive where necessary.
I suspect that experience of your h's recalcitrance is colouring your view but, no matter what he may initially threaten say to the contrary, I doubt your divorce proceedings will become unduly protracted once he realises that he will be footing the bill for the services of whatever firm of solicitors he instructs to act for him. If he chooses not to instruct solicitors I would suggest you/your solicitor negotiate for him to pay half of the total costs of divorce with the sum being deducted from his fair share of the equity.
Without knowing how much equity has been accured in the marital home it's not possible to give a considered opinion, but as you've said you are the higher earner and can afford the current mortgage payments I would suggest you explore the possibility of remortgaging in order to give your h his fair share and fund your divorce costs.
In the normal course of events the decree nisi is commonly granted within 3-4 months of the petition to divorce being received by the court with application for the decree absolute being made after 'the financials' have been settled.
If you set foot on the path to freedom now and don't waver, you may find yourself celebrating your emancipation during the festive season. 