In your case, you will need to create two marketing automation processes:
First one would be similar to your current one, but you would add a step that would add the contact into a contact group (e.g. ContactsWhoSubmittedTheForm). Then you would wait 7 days and check if the contact visited the page and continue further accordingly.
The second automation process would be set to be triggered by a page visit of the specific page. In the process itself, there would be condition step that would check if the contact is in the contact group (e.g. ContactsWhoSubmittedTheForm) and if yes, it would send you the notification email right away (so you wouldn't need to wait 7 days).
I hope it helps!