Ladybirder: Without knowing many exact details, such as husband's date of birth, it is simply impossible to give a precise figure.
My recommendation would be to call the government-provided Pension Advisory Service on 0800 011 3797. (Mon-Fri: 9am - 5pm, excluding Bank Holidays.) (This service is free & doesn't come with any element of selling.) Basically a widow can get the State Pension based on her husband's contributions if his contribution record is more complete than hers. For a widow who has never contributed, this is simple.
I believe that the widow has to make a claim to get this, but it can be done by a simple phone call. (This doesn't apply to widows born on or after 6 April 1953, as they come under the new pension rules.)