Quick summary answer: You must promote this using direct mail to businesses who are in the right geographic region to take advantage.

Buy or rent lists from: Chamber of commerce, local business association, local council rates payers etc. Also find organizations that have mailing lists and agree a deal with them to promote to their list.

Get each to send a direct response email that drives readers to your landing page which includes these 3 things
1 - re-iterate the offer
2 - give a guarantee of quality
3 - add testimonials

Have an on-page registration form to allow you to phone and qualify each enquiry.

As an additional benefit you could get firms to refer others to you for an extra discount if their contacts sign up.

Note you'll need a strong process for follow through to ensure nobody gets overlooked.

Go gettem!

This is an awesome promotion and really appropriate for SMEs I'm so glad you have gotten great support.
If you need help writing the landing page, or introduction email, please get in touch.