Am I eligible to british citizenship

[Chadimek]

Please help,
I'm born 1/2/1981 in lebanon and I'm single
My mom holds a british subject passport since birth.
She is born in lebanon 2/2/1948.
My mom's father is Indian who served for the crown and holds a british passport.dob: 1/1/1920
My mom's mom is Lebanese and holds a british passport.

Am I eligible for a citizenship?

[IndiMarshall]

Check if you're a British citizen
https://www.gov.uk/check-british-citizen

[Chadimek]

I tried it
But it's very confusing
I don't know if I have the right of Adobe . I never applied for any british documents.
Please help

[Amber]

Was he serving for the Crown when your Mother was born?

[Chadimek]

Yes he was

[Amber]

Assuming your Grandfather was in Crown service which at any time is designated by the Home Secretary or was in service under a European Community institution, then your Mother may be British otherwise than by descent, meaning you may be British by descent. Assuming your Grandfather was British when your Mother was born. Perhaps asking the Home Office for confirmation of nationality would be advantageous.

[Chadimek]

Thank you amber very very much.
Can you teach me how to contact the home office.
Tks again