Genealogy / Claiming WW2 medals for Polish father [38]

Where would I be able to find my fathers wartime service number he was Polish and on The Convoy. PQ16 to Murmansk and Archangel (1942)

My Polish father ( late) was on the ORP Garland a destroyer accompanying food parcels to Archangel and Murmansk in1942 on Convoy PQ16. I have a certificate to show my dads permission in July 1944 to land in Britain. What I don't have is his Naval Service number . Any ideas how I can obtain this. He subsequently lived in Edinburgh where we were brought up