Email design with button for Email consent

I need a designer who can create an email and a sign-up form for my company, who is looking at starting a mailing list. The email design must be colorful and in line with the company's colour (see www.followtherainbow.co.uk), include a "Opt in here" button to access the subscription page. I want my customers to subscribe to receiving promotional emails (which may include events that might interest them, etc) but need their consent first. I already have a Privacy Policy but need help with the design. Ultimately, I want my email to look something like "Asos email" attached.