What I am trying to achieve is automatic invoicing to customer after they have filled out my contact form.
what would be good if the script could automatically generate a pdf which quotes their name, product,date, and a message from me saying thank you blah blah blah.

but the pdf isn't essential even if it was just a html invoice quote the customers name, product, date, invoice number, upon completion of the form but the invoicing would need to be sequential so constantly increasing by 1 number some sort of auto generating invoice

thanks to all I've tried searching for tutorials but its hard because I don't exactly know what I am meant to be searching for to find this.

thanks & regards,