Unless there's something major happening down there this weekend, (fatboy slim gig / rally / etc) then you'll get a room once there.
you could try local tourist board - either before or when you get there, and they'll point you in the right direction.
At this time of year, there should be enough empty rooms, and although they'd like to have guests for the whole weekend, if the rooms empty on friday, they'll bite your hand off for the cash on the Saturday. I went with 8 mates last summer, and we all got rooms on the Sat, just by walking around for 20mins looking. Good Luck.