First find out where your local family mediation service is. They will charge, but a lot less than a solicitor. Get them to send your df some leaflets, then write to ex with a leaflet asking if she'll agree to mediation and say if not, he's going to make an application for a defined contact order.
If it comes to it, you can get the application form from the court or online on www.courtservice.co.uk. There is a fee payable.
He sends 2 copies of the application and the fee to the court and they set it down for a ten minute hearing. At the hearing, the court won't make a decision but will tell both parents to file a full statement of fact. In most courts they'll also appoint a Cafcass officer to meet both parents, new partners, the children and the schools and then to file a report giving a recommendation. The Court isn't bound by the recommendation but it does carry a lot of weight in the decision making process.
In theory, there'll be a final hearing but in most cases, if the Cafcass makes recommendations which both parties can live with, a consent order is filed, signed by both parties recording the agreement. The judge will just seal the consent order, making it legally binding.
Although it is possible to do these proceedings without a solicitor, it would certainly help to have one.