Hi vPeter,
Hanadama and AAA are very, very similar. But Hanadama is lab-certified and AAA is not. Hanadama is basically the best of the best AAA.
Regarding a supplier in the UK, try Selectraders,
http://www.selectraders.co.uk/akoya-pearls-2.html.
The PearlsOnly Web site is not in the UK. They are based in China and their pearls ship out of China. They have no UK office.