Jayne,
Take this route;
https://goo.gl/maps/uWTUKHgSWBz
It is a little bit longer, but, you get to see the lovely scenery of Wales as you go over the Heads of the Valleys road, also, going that way you can stop in Abergavenny, it is a big biker meet area, so, good areas to leave the bike and grab some drinks and make use of the facilities if you feel so inclined or you could visit Raglan Castle.
You'll ride past where they are going to be building the new MotoGP contracted race track in Rassau, you could visit Cyfarthfa Castle in the area too.
You can then pop into Penderyn for some Welsh Whisky, ride past the lakes at Cwmgwrach, visit Aberdulais Falls near Tonna, you can then make use of Pont Abraham services at the end of the M4 before your trip along the A48, which has the National Botanic Garden of Wales near Porthyrhyd on the way.
Lastly there is Pembrey Race Track near by.
Hope this gives a few pointers