P20 sunscreen: how much needed for a one week holiday?

[verygreenlawn]

Two adults and two dcs 6 and 5 - one week in the sun. Dcs will be wearing UV suits and hats, adults will be a bit more uncovered (but we tend to stay out the sun quite a bit anyway, being deathly pale).

Any idea as to how much we would need to take with us? Thanks.

I'd say two good size bottles ought to do it. One for you and one for dc's-you might want diff SPF's.

Thank you!