W,
Welcome
On abattoirs if you are doing a private kill - ie for yourselves, then November should not be a problem, as those that cater for private kills are used to all year round and 4 should not be a problem. A local butcher will be less keen on cutting for you in December, but an abattoir's cutting plant if they are butchering will work all year.
From your point of view, November just give you a potential of more mud, but this will depend on weather and your ability to move them to fresh ground if needed.
Many of the smallholders who buy from us have pigs outside all year round.