Mediation is a dispute resolution process that can work for many couples. The mediator is a neutral person who can help you to make decisions about some or all of the issues relating to or arising from the separation or divorce including children, finance or property.
You need to instruct a mediator in the first instance in any case because before making an application for a financial order to the court the rules say you must first attend a 'Mediation, Information and Assessment Meeting' (MIAM).
Only mediators accredited by the Family Mediation Council can sign a court form to say you have been to a MIAM.  Please ask the mediatior, can they sign the court form to say that you have been to a MIAM? 
At the point of making the application to the court  we would need the mediator to sign section (4b) of the relevant form, 'Form A'.
Legal aid is still available to help fund mediation and it may be that this is available to either you or your former partner. If this is not an option, the precise cost is difficult to estimate, and will need to find out the specific costs from the mediator when you are referred.

Laurence Holmes Solicitors in Bristol