There was a programme on BBC 4 on the 22nd August 2016 at 16:30
This was a talk on Sharia Law or Councils within the UK. Whilst it as not compulsory for a Muslim to use it and it as no backing of UK Law, which is still Primary Law of the UK.
It deals mainly with family law, divorce, inheritance, custody of children etc.
What came out of it was the suggestion of all Muslim marriages in the UK to be registered by the register office official in a similar manner to anyone else who gets married in the UK.