As much money as you have , there is no limit to it it could cost £millions if you were both millionaires. No legal aid is available for divorce cases now so the sky is the limit . When my daughter wanted to contest a divorce she was told that nothing could be done until she up £10,000 as a starter to prepare a case.
Solicitors letters were £50 to £250 each !
A day in court - for a professional matter, a friend had to cough up front £10 000 - and since it was destined to last six days - that was sixty big ones up front
Why bother ? If one spouse wants a divorce, even if it means waiting a few years, it will go through eventually. You can't chain someone who doesn't want to be chained.
But if you are talking about the settlements, child custody, who gets the house - and you are talking about getting a judge to settle these matters if the spouses can't agree, then tens of thousands, probably.