Rail, air and Post Office users face a week of major disruption with strikes and engineering work causing misery to hundreds of thousands.
At Southern there are two days of strikes by guards on Monday and Tuesday.
They will walk out again over the New Year holiday.
The dispute is about the role of the guard and driver only operation.
A strike by main Post Office workers is set to cause disruption all week but will not hit mail deliveries.
Some branches could close or have longer queues.
The dispute centres on jobs, pensions and branch closures.
1,500 ground staff who work for Swissport at our airports will strike on Friday and Christmas Eve in a row over pay.
Southampton could be the worst hit as the company provide all its ground operations.
Bournemouth, Heathrow and Gatwick could also be hit.
Virgin Atlantic pilots will stage an overtime ban for a week from Friday in a row over union recognition. Flights could be hit.
2,500 Britsh Airways cabin crew will strike on Christmas Day and Boxing Day.
BA will announce its contingency plans later.
This dispute is over pay.