The initial idioms of the letter B

be money for old rope	be more Catholic than the Pope (himself)
be more trouble than it's worth	be mother
be much cop	be much of a muchness
be much to look at	be music to (one's) ears
be music to ears	be my guest
be near the knuckle	be near to impossible
be no good to man or beast	be no question of (doing) (something)
be no question that (something will happen/is the	be no skin off (one's) back
be not (one's) bag	be not having any (of it)
be not (one's) cup of tea	be not in Kansas anymore
be not just another pretty face	be not much cop
be not much to look at	be not on
be not rocket science	be not short of a penny (or two)
be not the done thing	not up to snuff
be nothing much to write home about	be of (one's) own making