I have a wordpress + woocommerce page. I have two different checkout pages.

1st Klarna checkout. a plugin that requires its own custom checkout page.
2nd ordinary woocommerce checkout page.

What I want to do is to use JavaScript or jquery or something, I dont know? On the cart page there is now a button that sends customer to the checkout page. I want to disable it if you have not filled in several fields. The fields must also be added to the Cart.php For example first choice to choose is country through a dropdown. Second choice is to choose the payment method by radio buttons. Based on that is be sent to either the checkout page 1 or 2.

I dont have any skills on either php or javascript. Could someone please help me.

Best regards Alex.