How can I attach my newly created booking form onto an email to a customer?

Hi,

To clarify, are you referring to sending your form through email? If so, here's a detailed guide: 

1. On the Form Builder, click PUBLISH at the top.

2. Then, click EMAIL on the left nav.

3. Click the SHARE ON EMAIL.

4. On the next page, customize the From Name, To, Reply To, Email Subject and Body of the message.

For your reference: How-to-Send-a-Form-via-Email

I hope this helps. If you are referring to a different query, kindly provide us more information to further assist you.