In reply to Andy S:
Depends on which way you go. I have done it via Dieppe, longer ferry crossing but shorter drive in France. Channel Tunnel is (usually) faster than a ferry but gives a longer drive on the other side. Also depends on time of day- the direct route via Paris is a nightmare at certain times. For me, from Birmingham, the tunnel/Dover/Folkstone ferries is between 3 and 4 hours (depends on what the M25 is like). Font from Calais is around 4 to 5 hours, again, traffic dependent.Use Google maps or Via Michelin to work out times.