http://www.theguardian.com/world/2014/may/12/muslim-scare-st...
On closer inspection, it is clear sharia courts only have jurisdiction on civil matters and everyone must opt in to a sharia court. They only have an advisory capacity and address mainly property and financial matters, and rulings are then only enforceable by civil courts. In many cases, they are understaffed affairs, where one official settles petty disputes and draws up rudimentary documents.
So just like any other kind of alternative dispute resolution - mediation, adjudication, expert-determination, arbitration etc.
Edit - I'm actually over-stating this last bit, "sharia" law isn't nearly as strong as these formal ADR mechanisms.
Opting out of these courts may not be an option for women pressured by their families and communities.
I'm not trying to say that there won't be problems with these kinds of mechanisms, but if UK citizens want to get together and try and work through a dispute based on some religious principles and all parties agree then I don't think we should be trying to stop it.