My family, which includes my husband and our three childen had a ten break in St Quentin. We stayed in a town house not far from the town's main square. The house was fabulous and there was so much to do. The main square strangly converts into a beach with all activites free including swimming, face painting, trampoling and catch the duck, which my two year old most enjoyed.
We did not even venture out of the town as there was a nature park nearby with additional activities to please all the children. A great holiday on a budget. We shall be returning.