Selling Gift Vouchers for Treatments

I would like to sell gift vouchers on our webshop that people can print out and redeem in our salon.

We are a beauty salon and sell vouchers in the salon. So someone comes in and wants to buy one. We write either "Treatments to the value of £" on the voucher or "An Aromatherapy Massage". Then we sign it and date it.

Is there any way to include these vouchers on our webshop? Either monetary amounts, treatments or preferably both.

I would like the voucher to be emailed to them so they can print it out, so it needs to look nice enough to give to someone.

If you need to see my webshop it is: https://www.taylormadetreatments.co.uk/webshop

Please don't judge too harshly, I am a real amateur so it's by no means perfect!

How about using the built-in Gift Certificate function ?

I thought that was for Gift Certificates to use on the webshop? I need certificates to use in the salon, not online. Or have I mis-understood the built in certificate function?