“Is it correct that mediation is not binding? If so, this sounds like an attractive option.”
You need to distinguish between two different things here. You have a choice about entering or abandoning a mediation process, (although having signed an agreement to attend and to pay for it, it would be a strange decision not to attend). The process of mediation is therefore not binding.
If (as in over 80 per cent of cases) you settle your dispute, it will be drawn up into a written Settlement Agreement. All parties will sign it, promising each other to abide by the terms agreed. This is binding as soon as signed because you and the other party agreed that this is what would happen (a clause in your earlier Mediation Agreement). The process is not binding but the Settlement Agreement is.