what percentage of seats are available for pre-alloc?

Hi
just booked spring 1/2 term flights LGW - MCO, UC out, PE return.
pre-allocating the UC seats was no issue, but all but two PE seats are pre-allocated (different decks too). needless to say Mrs W is having an OMG moment as we're travelling with a 9yr old and she always fears the worst when it comes to airline seats but i'm re-assuring here that at T-24 and OLC there will be more seats available.. but.. does anyone know what percentage of seats were available for pre-alloc typically?
thanks
Leighton
just booked spring 1/2 term flights LGW - MCO, UC out, PE return.
pre-allocating the UC seats was no issue, but all but two PE seats are pre-allocated (different decks too). needless to say Mrs W is having an OMG moment as we're travelling with a 9yr old and she always fears the worst when it comes to airline seats but i'm re-assuring here that at T-24 and OLC there will be more seats available.. but.. does anyone know what percentage of seats were available for pre-alloc typically?
thanks
Leighton