Fliss, sorry you missed out on 'The Flanders Experience' when it was running but it's not hard to DIY.

Ferry's can cost under £50 for a car with 4 people and I would point you at Talbot House as the ideal place to stay. The history of the house makes it worth a trip over there on its own! A self catering bed there costs E45/head
Talbot House web site
There are multiple 'must see' museums in the Ypres Salient: Flanders Fields in the Cloth Hall in Ypres, The Pachendaele Museum in Zonnebeke, The Hooge Crater Museum and the nearby Hill 62 Museum and, of course, the cemeteries at Tyne Cot and Langemark. If you are staying at Talbot House, you automatically get entry into The Toc H museum which has been created in the warehouse next to the Garden.

Pm me and I can give you a suitable reading list etc.

To get the best out of a trip to Flanders, your best bet is to contact Jacques Ryckebosch at Flanders Battlefield Tours.
http://www.ypres-fbt.be
Tell him I sent you, this won't necessarily get you any favours, but I'd like him to know!

All the best,

BobH