Theres a fantastic offer currently from P&O Ferries but you need to act fast so I suggest you book your daytrip tickets to France now.
You need to book a Dover to Calais daytrip before 26th February 2009 to get this deal for travel up to 31st March 2009.
Basically you will get 2 deals as part of this offer.
2) You will get a buy one, get one free offer for either breakfast or dinner in the onboard food court.
This is a great deal considering that the return trip can work out at only £19 for a car with passengers. This leaves you with more cash for shopping in France.
To take part in this offer just follow this link here.