CRM for a small business

I have a website with a webform where customers can fill in a few details.

This comes in as an e-mail on my end.

What I’d like is a CRM where the inquiry comes in, and all communication goes through that. So: inquiry > reply from me > get a notification 1 week later to follow up if prospect hasn’t replied etc.

Ideally something that’s free/cheap since I’m a SMB.

Any suggestions?