Hello ChrisH939,
Yes, you are right Mechanize is the best module for Python, for this kind of job, Mechanize actually lets you browse to pages and input data on web page. The best thing to log onto a website and submit in specific time is cron-tool for linux, i don't know what OS are you using, but linux is the best option. I've a lot experience in web scraping,submitting data on the web and i am very experienced in Python development, so i will complete this project without any problems.
Best Regards,
Stevan