Thanks for the Heads up !! I’ll probably have ended up getting stuck as I have the A8 7600 GPU 
I came to Ubuntu Mate after having issues with Mint and was so glad Catalyst worked out of the box.
What options have I got ? - obviously moving away from Ubuntu to another flavour is one - but which and will Steam still work? Replacing the AMD mb is not an option as the PC is 8mths old. I fear reverting to W7 may be my only option (it will please my children as all the Steam games they like work on W7, unlike now).