my partner has been separated with his wife for 13 years, he is now a british citizen by descent. i was given entry clearance to join as partner. we want to get married here in UK.

need help on:

do we have to get a divorce first or we can marry right away without filing for divorce?

fastest way to get married without filing for divorce

can my partner not declare his previous marriage since he is now a british citiZen?

please help

thank you