Overnight support for parent of ASD teenager

Our daughter is 17 with autism, depression, anxiety, insomnia. Most nights are OK but some are very challenging, and time consuming.  My wife is unavoidably away for a week in March and I’m considering whether to get some support overnight, as if anything major happens I can’t also look after our son. Is anyone  aware of any respite services that I can access, for support at our home, either there overnight or ‘on call’ should I need support?  Buckinghamshire, near Amersham.

Thanks