Now that the cold weather is approaching, what are everyone’s thoughts on waiting for the engine to warm up. I only have a relatively short commute of about 5 minutes but after the snow last year I don’t want to be stuck.
Is it better to allow the engine to warm up and if so how long? I have a Puma Defender

Even a five min drive is no where near enough to get an engine warm and not even long enough to demist the screen. Just start and give the motor a few secs to settle into smooth running and circulate the oil some and away to go. You can get some anti fog for the screen and a can of deice spray for when it gets below 0. The only other thing is fit an electric preheater that plugs in on a timer and warms the engine/heater before you get in.

As above really. More harm will be done by sitting in the vehicle waiting for the engine to warm up.
Just get in and drive it normally. Obviously don't thrash the engine while it's cold, but you wouldn't do that anyway.

Consider fitting a heated windscreen if yours hasn't got one as standard, it's not that difficult or expensive on a Defender.
lt's probably the best single extra l fitted to mine.