Hi Kernow - we are only closing for a half-day on Xmas and New Year's eve and the full day for Xmas Day and New Year's Day. However, some companies have already closed for the holidays and won't open again until after the Kings on the 6th January.
As for the building trade, business is pretty tough at the moment so they may well be open throughout.
Like most things here - people tend to make up their own rules!!
Feliz navidad