This is where I am with this.
Still can't get the Add to cart behaviour to work.
So I used my time machine to restore the files as they were first thing. the application page now loads so I tested the process. When directed to the checkout page, the form has the validation issues ( uk phone number not accepted ) So to test the process further I just used a us number but when I submitted the form it doesn't direct anywhere. So I manually entered the path to the confirm_cart page and it has the details there but no button to press to proceed. I thought these pages should be all connected and working so that you get directed to 'Express Checkout'. and then make a payment.
Not sure where to go with this.