~snip~
Could I get a wallet I use just for that? Where I can leave the payment QR code in the email and people can scan it if they choose to pay via Bitcoin?
^ It was explained above and I also prefer Electrum wallet which is very easy to use and has a simple user interface.
You can generate QR codes and print in anywhere, you can even capture a picture and send them anywhere that you wanted. But a piece of advice, instead of sending an image of a QR code only, why not send them also your BTC address so that it is easy for them to copy and paste it to their wallet?
There are a lot of process in Youtube regarding this, probably it is also good if you will find your own research.