Do you have any music subscriptions services such as Deezer, Spotify Premium, apple music or amazon prime or Amazon Unlimited music? If you have any of these; they are either automatically enabled or for the NON-amazon ones you would need to add your credentials in the relevant skills in the Alexa app.
Be aware that there are no bundled music subscriptions that are free with the Echo purchase.
To check that your Echo can play music, try "Alexa, play <BBC Radio3> from Tunein".
Thanks for reply Peter, I have prime subscription. It's the echo plus device. Surely I don't have to be on the Amazon music app and connect via b tooth to play music. I did this and it worked with the device.
I'm sure you are right. You will need to register your devices into the same region as your streaming subscription. If you use the same address for both .com and .co.uk I think you will need to contact Amazon tech support via the call back links on the help pages.