Belleville Lake is located East of Ann Arbor. Depending on what part of Ohio you're coming from you could take 23N to 94E (75N to 275N to 94W) and get off at Haggerty Road. There's a boat launch for Belleville lake at Sandy's Marina (I don't know if there's a charge to launch there). Or you could get off at Rawsonville Road (a longer travel to be in the main part of Belleville Lake, but it doesn't cost you anything).
I'd rather be on the lake enjoying the thrill of my rod telling me there's a fish on the end of my line. :D
Corey