Started car in gear, forgot clutch (!!!) And car jerked. Result was no power, lights etc, battery dead. Tried to jump start but wasnt happening.
Any advice greatly received
Don't jump start it, you can spike the BSI.
Google "Peugeot BSI reset" and see how you get on.
If nothing electrical works, It maybe one of the battery leads has failed due to overload or has poor connections.
I would agree - check your battery connections.