Entry clearance is given for six months, during which time you will not be allowed to work. You must show the following:
that you plan to marry or register a civil partnership within six months of arrival in the UK (though in exceptional circumstances an extension of this time-limit is possible)
there must be a place for you to stay before your marriage / civil partnership (this can be with your prospective partner, or elsewhere)
there must be sufficient funds to maintain you without working and without access to welfare provisions.
Once you are married you can apply for leave to remain on that basis. You will be granted an initial period of two and a half years, after which you must extend your leave to remain for a further two and a half years before you are eligible to apply for settlement.
There are no restrictions on working after you have been granted leave to remain as a spouse of a person present and settled in the United Kingdom.