Many on this thread do not seem to realise that there is just ONE reason for divorce now ( and has been for years) that reason is, that the marriage has 'irretrievably broken down'. There is no concept of 'fault'or 'blame' any longer.
If one or both partners are on a low income or income related benefits , then a rebate of the court fees is available. So it make financial sense for the partner on the lowest income to start the divorce, as they have the best chance of getting the rebate.
Best people to contact for help are your local CAB. DO NOT !!! get a solicitor involved , they are after one thing only 'to make as much money out of the situation as possible'.