You can pay both by Paypal and Credit Card or Debit Card.
To do so, once you have added the product(s) you wish to purchase to your basket, click on the green "My basket" button on the top right corner of the screen, and then "Proceed to Checkout".
Once you've filled in your Shipping details on the next screen, you will be able to select a Shipping method and hit "NEXT".
On the new screen, under Payment Methods, select SagePay to pay by card.
There you can untick the below option if your billing and shipping addresses are different and hit "CONTINUE TO SAGEPAY".
You will then be redirected to the Sage Pay website, where you can pay by card.
Click on the type of card you have and then enter your details and hit "Confirm card details".
After that, you should receive an email confirmation soon. Please check your Junk/Spam folder, too.