Agree with previous posts.
It's about 60 miles from Calais to Ypres (now called Ieper) - you can blast along the motorway to Dunquerque and down the N8, or come aff a little earlier and go through some of the villages (such as Poperinge). The countryside and villages are nothing much actually - although once you're in Ypres all that changes. When you look at the Cloth Hall and church in the centre of town, it's almost impossible to believe they were razed to the ground by German shelling and completely rebuilt after the war. Tell you something - the Belgians NEVER forget that war - unlike this country. Kids at school still learn about it and it's taken very seriously indeed.
The museum in the Cloth Hall is an absolute must-see - probably have you in tears...
When we were there, we met an elderly British couple sat outside one of the cafes on the main square. Turns out this old Geordie guy's grandad was billeted in Ypres in WWI. He and two mates sold an artillery horse to a local innkeeper for four bottles of rum. Went back to their tent, drank one bottle, buried the other three and that night went into town and stole the horse back!!
Getting there? Check the prices on the internet - we ended up with a fantastic deal with Eurotunnel, which get's my vote every time for cross-Channel (if the price is right).
Have fun and bring lots of tissues - it's an emotional rollercoaster.