I'd say go for it! If your riding buddies are worth their salt, they'll be happy to ride easy while you tackle the hills - and you may surprise yourself and do better than you think.
The best advice is to pace yourself and to use your gears - don't mash up the hills, spin in a nice easy gear that will give you enough resistance to climb steadily. Hills are definitely as much of a psychological battle as a physical one. Don't focus on getting to the top, just keep turning those pedals and focus on your form and your gears.
Good look in advance!