a bridge too far

as far as one knows

To the best of one's knowledge, as far as someone knows or possible information to be gathered about the topic, subject, aspect, or situation.

bridge over troubled waters

Someone or something that provides support, comfort, and a means to overcome difficult times.

bridge the gap

To serve as or create a connection between disconnected or disparate things.

burn that bridge when one comes to it

To anticipate dealing with a problem or situation either by acting in a manner that alienates or cuts ties with others, or merely with the expectation of encountering trouble.

cross that bridge when one comes to it

To deal with a problem or situation only if and when it arises.

far and away

By a large degree or margin; greatly (used before comparative and superlative adjectives).

far be it

A disclaimer stating that something should not come to pass, or that a person would never do or think a certain thing.

far cry

A long distance, in terms of dissimilarity or difference.