You need to read this page and How to apply for a UK passport to have all the information you need to apply for your passport.
Where to apply

Resident in Bahrain

If you live in Bahrain you should apply for passports at our Manama office:

British Embassy
21 Government Avenue
P O Box 114
Manama
Kingdom of Bahrain
 
Embassy Main Opening Hours
Sun- Thur: 07.30-14.30 hrs
Sunday to Thursday
Consular Opening Hours
0800-1300

You can also:

• post your passport application form to either office if you are paying the fee by bank draft
• make postal requests for passport application forms to either office

What to submit

To apply for a UK passport in Bahrain you must submit:

• your completed application form
• your 2 passport photographs
• your supporting documents
• your previous passport
• the correct fee

If you are sending your passport application by post, you must pay the passport fee(s) by cheque.

Processing your passport application

It takes 10 days to process your passport application from the date we receive it.

Our staff will not be able to process your application or there may be a delay issuing your passport if:

• you have used the wrong form or completed it incorrectly
• you do not provide the correct fee
• you do not include the correct postal or courier charge.