Yes, the form is available in TurboTax and can be E-filed with your return. TurboTax will collect your relevant information when you're working in the state portion of the program.
It sounds like you're having trouble finding where to enter your credit information in the Michigan portion of TurboTax. To get to this section in TurboTax Online:
You don't need to send Form MI-1040CR-7 separately from your Michigan return, if you're filing a state return.
If you aren't required to file an MI-1040, you can file your Home Heating Credit Claim by submitting form MI-1040CR-7 only. You would mail your claim to:
Michigan Department of Treasury
Lansing, MI 48956
See the MI-1040CR-7 Instructions available at Home Heating Credit Information for more filing information.