I'm using the popular wordpress plugin called Contact Form 7. Its easy to redirect the form after submitting to any page by adding this code
on_sent_ok: "location = 'http://example.com/';"
Just use this hook:
on_sent_ok: "location = 'https://gettinmobile.com/my-account/checkout/?level=1&' + $('form.wpcf7-form').serialize();"
This will append all the form data as parameters in the query string.
Cheers, from La Paz, Bolivia