They are lovely pets, social creatures and eternally kittenish. Yes they smell, they are hard to housetrain and they are buggers with the soil in a pot plant!
BUT... you can indeed walk them onlead and train them to walk offlead if you put enough into it and you have the right ferret and a well chosen one from a reputable rescue will be matched to your novice, child-including family so you won't end up with a biter. :)
We have one - he's a fantastic pet.
An alternative would be a pair of rats. Don't laugh (or scream!), they're intelligent, smart pets, very clean and trainable and easy to handle.
Just please... go to a rescue who will match the right pet to you and don't ever go to a pet shop.
A decent rescue will neuter, vaccinate and assess the pet, insist that he comes back to them if you can't keep him, even if that's years down the line, and homecheck the owner, for the sake of owner and family as much as for the sake of the pet.
If you're near Cambs I know a fantastic rescuer and I also know a great ferret rescue in the North East. Shout if I can help. :)