As far as that redirect goes. Why don't you do an .htaccess rewrite.
Something like this:
RewriteEngine on
RewriteRule ^index\.php$ week.php
Just create an .htaccess file in the events folder and then add them two lines above. I'm still new to rewrites but I believe that would work.
I think you forgot to resend your form variables to the check.php page. You are just checking form_set then redirecting if it is true. So no $_POST variables are even being sent to check.php.
I could be way off. I didn't read all of your code.
We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.