Providing it was frozen within the use by date, it can be stored for up to 3 months.
Also, a common misconception with dates on food is that a best before date is the same as a use by date. A use by date is a QUALIFYING date, and so therefore must be consumed by that date, unless you choose to freeze it.
A best before date is merely a recommendation, and food can still be safely consumed, in some cases, up to 6 months after the given date.
Contact your local environmental health and ask for a leaflet called, "Understanding Food Labels" and that should tell you all you need to know.