1. You can apply for UK citizenship after five years of marriage to a UK citizen during which you were residing in the UK. So, you are eligible to apply for citizenship. HOwever, it is a requirement of citizenship that you are able to show that you were living visa free in the UK for one year before your application. It is for this reason you need to have a Permanent Residence card for one year before you make your application. So, you will have to apply for a Permanent Residence card and hold it for a year before you will be able to successfully apply for a UK passport and citizenship. Here is a link to the UK Government website which explains how and why you get a Permanent Residence card https://www.gov.uk/apply-for-a-uk-residence-card/permanent-residence-card
2. Here is a link which explains the process of applying for UK citizenship where you are married to a UK citizen https://www.gov.uk/becoming-a-british-citizen/if-your-spouse-is-a-british-citizen. You see you will also have to pass a Life in the UK test as well as paying an application fee.
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