Help! Child Benefit Stickers

[Kitten_sox]

I've just finished filling in my Child Benefit forms and noticed it says I need to fill in the enclosed address stickers...but I have no idea where they have gone!
If I send it off without them will I still get Caitie's birth certificate back or do you think it is worth going out and buying a packet of stickers just to be on the safe side?
Silly Baby brain!