Don't be scared of doing a sprint. There is a lot to be learned from racing sprints and working your way up to a HIM.
There are people of ALL speeds out there. Trust me, I'm not a sprinter, but somehow I gut it out.
For example, tomorrow I have a sprint tri... with a 300 yard swim. I don't feel warmed up in the water until about 600-800 yards in, so that's going to be my warm up. This body is not made for sprinting, let me tell ya!
Doing tri's is a journey. Part of the journey is experiencing all the steps that lead up to a HIM and an IM. It's also nice during HIM training to have some races along the way to keep your training interesting. Honestly, training for 3-4 months without a race, well it's hard to keep focused on a race so far out. It's very common for people training for HIM's and IM's to do sprints/olympics/HIM's before the big race.
Well, good luck in whatever you decide. I say, train for a sprint early next year. It's the perfect first step into the world of triathlon!
"Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather, to skid in broadside thoroughly used-up, totally worn out, and loudly proclaiming: WOW WHAT A RIDE!!!!"