Whn you say the shutter speeds would not work how do you mean?
First tip, buy a 50mm F1.8. This will let in approx 3 stops more light than your current lens. For you this means if the exposure suggests you need 1/30th with the 17-85mm you can get 1/250th with the 50mm F1.8. Also the autofocus will have an easier time because it has more light to work with.
You can use flash as an alternative too. Set the camera to Manual. 1/250th ISO 1600 and the widest aperture possible. Mount the flash on the camera in ETTL mode. Ensure AF is in servo mode and just have a go. Then based on the exposure you get adjust the flash compensation accordingly.
If you are still getting inconsistent exposure you will need to switch the flash to manual too. This requires a little experimentation and a bit of reading beforehand. There is a chart in the user guide for your flash that gives you the required power for a subject distance and aperture - start with that.
Autofocus will be the most difficult thing to get right in the low light conditions with the 17-85mm. It is possible just much harder because the lens lets less light in.