Hi Anthony,
As Alan/Whitty says in his response - the area you refer to is the tidal stretch of the Severn estuary - from memory it is very muddy and you could well lose yourself and /or the kids there!
The Wye flows through Chepstow and is known as a Barbel river - but the favoured stretches are expensive/exclusive and Alan's tip on the Foundation may be the best place to start.
What sort of fishing do you normally do for Carp? - Stillwater?
Fishing a river is quite a different kettle of .......
mg: ... - sorry!
One of the big problems on many rivers - especially the Wye - is accessability down the banks - and getting back up them! There are a few members of this forum that can attest to that!
I'm hoping that there are some members more local to the area that will be able to give you a better steer on the local fishing. Whereabouts are you based and what kind of waters do you normally fish - and how old are the kids?
Tight Lines :thumbs: