There's tons of videos out there nowadays on Youtube that show full races with race metrics (speed, power, cadence, etc), if you want to get a sense of what races are like. Look for Cat 5 races — that's the level that you'd be entering in as.

In general, a Cat 5 race will require you to be capable of averaging ~24mph (while drafting) for ~45 minutes. But until you actually join a race, you really won't know what you're capable of and how large the gulf between your level and that of everyone else in your area is.

If you're interested in racing, come over to /r/Velo and check out our ELICAT 5 series (linked in our sidebar). Lots of good stuff for beginner racers!