No - you do not automatically become a British citizen because you are married to a British man or woman.
Before 1949, if a woman married a British man she automatically became a British citizen. This is no longer the case.
We cannot help you to apply for British citizenship. You must do this through the Home Office. If you have any questions, you can contact them using the following address and phone number:
General Enquiries Section
Home Office Nationality Group
PO Box 306
Liverpool
L69 2UF
Their website is at www.ind.homeoffice.gov.uk (new window). They can also be contacted via telephone on 0845 010 5200 between 8.30am and 6pm Monday to Friday excluding public holidays. Please note that this number is heavily subscribed to and you may have to be patient in getting through.
24-hour Passport Adviceline: 0300 222 0000 (see terms and conditions). Calls made to 0300 numbers from landlines and mobile phones are charged to customers at their network provider's national rate. Live operators are available to assist with your enquiry 24 hours a day.