Research help

Good evening,
I am looking for a little bit of help, I am currently researching my late grandfather who we believed served in Fleet air arm during WW2.
My grandfather, Roland Avery I believe served in Singapore during the war which I guess was HMS Simbang/ Sembawang. I am currently applying for his service records to confirm this.
I know his service number was JX619778.
I am trying to surprise my father with as much information as I can, due to no family members have any details.
Thanks for any help that I can clean.
Many thanks
Is anyone able to confirm what his service number relates to.
That is the only detail I am able to obtain at present but I am unsure if I am correct in thinking he was fleet air arm.