You can add your lead capture form to your Facebook Messenger Auto-Reply, by going to your Business page settings in Facebook:
Click on Messaging, and scroll to "Response Assistant"
Turn on "Send instant replies to anyone who messages your page"
Edit the "reminder message" to say something like "Please fill out our contact form below so we can work on generating a quote for you!" Then add the link to the Lead Capture Form from 17hats (use the "View Form" URL)