So, embarrassingly, it was my fault - again!! The issue was with my client - NOT the astroberry server!
I did a complete refresh again and also built a new client Ubuntu device - and it connected straight away! So I started digging and discovered the original client had some hard-wired network config in it, probably from previous testing!
So, I am going to retry the astroberry_wireless script on the original SD card, but I am pretty confident it will!!
Many thanks for your support Radek - but it seems it was my fault!!