Upgrade on Prime Music (40 million songs v 2 million).
30 days trial then:
£3.99 a month for Echo users (via Alexa) (note - plan tied to a single Echo or Dot)
£7.99 a month/£79 a year for Prime Users
£9.99 a month for non Prime users
£14.99 a month/£149 a year for Family Plan (up to 6 family members) (Coming soon)