Before opening all the bottles, I would give each one a shake to resuspend the yeast and put them some where that is 70F or a little above and doesn't have large temp swings. English style yeast tends to drop out of suspension pretty easily, especially if there are temp swings. Two weeks is not a lot of time for bottle conditioning.
If you do decide to add yeast to the bottles, you will only need to add a few grains of dry yeast to each.