I can't speak for quetiapine/Seroquel, but if you're just looking for a sleep-aid, there's a few OTC options. I mean, Seroquel makes you sleepy by blocking histamine in your brain*, which is the same as any anti-histamine. So diphenhydramine/Benadryl, or like Mr. Mobius said, doxylamine.
They all have side effects, but I think Seroquel has a worse profile. I used diphenhydramine for years, and as long as you stay around 50mg and get at least seven hours of sleep, there aren't any noticeable side effects (for me; one issue is I think it ruined my teeth by drying my mouth out every night).
As for drugs roughly in the same class, there are alternatives like hydroxyzine or doxepin. Just tell your doc it's not working out; there're plenty of options.
*and it's an alpha blocker.