Oh no! Poor Zander (and poor Mummy's camera)!

Take the lens into a camera shop (not sure what's up your way but there is a big one in Melb CBD which has a repair centre attached) and get them to take a look. Depending on how it landed, it may have damaged the inside. I dropped one once (face first. Tripod blew over in the wind... Never ever EVER leave a camera on a tripod unattended! LOL); the outside of the lens looked fine but I had actually compressed the insides... Bonus for me was it was a manual SLR and DH went and bought me a brand new Digital the next day! WOOHOO!. But I hope yours is ok Sarah. If it is broken, see if your contents insurance will cover any repairs/replacement.

MG