awqward
In the UK licensed airfields have a minimum visibility requirement of 150m for takeoff. This is imposed by the airfield not a limitation on the pilot. A private pilot has no such limitation.... I'm sure you have practised take-offs under the hood... Of course none of this is sensible, especially in a single engine aircraft... a sensible minimum should be the visibility and ceiling required to land back where you took off from
You do have a minimum in a multi engine aircraft, and that is to be able to return to the airport you took off from and legally commence an instrument approach in the event of an engine failure, or have a suitable take-off alternate within 30 minutes single engine flying time.
Also is additional training not required to take-off in less than 400m as it then deemed to be low viz ops.
If you are operating single pilot is it not a requirement to have a minimum of 800 RVR to commence an approach ?
Of course that would not be applicable in a single engine aircraft should the engine fail.