For the people coming by car, you can find parking areas next to the temple. On active days, you might need to make use of parking facilities and after that consider an vehicle rickshaw. Here's a chart of the common ticket rates and transportation alternatives offered from Ujjain to Omkareshwar: https://bookmarkshome.com/story5191951/the-fact-about-ujjain-to-omkareshwar-by-taxi-that-no-one-is-suggesting