Touring - European route suggestions

I;ve got 6 days at the beginning fo April next year. I;m looking at a max of about 250 miles. My friend and I were thinking of North France and Belgium (specifically the Somme and Flanders - a tour of the WW1 battlefeilds), but I;m a bit concerned that the weather could be against us - In the UK, were I;m from April can be a bit brutal, and I suspect Flanders will be much the same. It;s convenient in that we can catch ferries to Calais, but we;ve been thinking that flying might be better, and as such, we;re looking for suggestions. Only Europe, though.
We kind of like history, so would like somewhere with a bit of a historical resonance. I was wondering about the Romantic Road in Bavaria, but again am uncertain about the weather. I don;t mind cold so much, but not wind and or rain.
I was wondering about Spain or Italy.

Anyone got any good routes that fit the above?

Do the Camino de Santiago in Northern Spain. I did it last summer, and it was great!

Thanks for that. What was it like, hilly, flat? ALso, how did you get there. DId you fly, and if so, was it difficult. I've never flown with a bike and imagine it's a nightmare these days.

Oh, also, where did you stay on the way?

Pretty hilly indeed, but nothing horrrible. The toughest climb is getting into Galicia in northwestern Spain, near O Cerebrio.

Actually, I rode there from my home in Germany, but if I were you, I would take the train from London to Paris, and then from Paris to Burgos. The Camino de Santiago runs directly through Burgos.

I hate flying. I only do it to visit the folks in Florida.

There are hostels in every little town along the Camino as it is an international pilgrim route. It's not just for pilgrims though. It is attracts a lot of people who just want to go on a nice long tour.