I don't think my ex is reasonable, is it worth even trying mediation?
Yes, many people think their case can't settle because the other person is too unreasonable, but these cases frequently then settle. That's what mediators do! The fact is, for a lot of people, the cost of arguing exceeds the value of the difference between them and, in those circumstances they should always try to agree things. Mediation is a good way to see things differently and compromise, as you do not become opponents in a fight, trying to sustain extreme positions.
My spouse gets legal aid for mediation, I don't. Why should I mediate?
If one of you gets legal aid and the other doesn't, the person who has to pay will only pay half the mediation hourly rate. Mediation is quicker than other dispute resolution processes, it takes less time and you only pay for half of the cost of that. In typical three session mediation with two summaries the cost will be under £800 for one person. That compares well with the costs of sorting it out any other way.