Wallet not working on Apple Watch SE

I used to be able to use Apple Pay on my watch using my debit card, now I can't. Nothing happens when I open the Wallet app on my watch and the screen reads Get Started Keep all the cards, keys and passes you use every day all in one place then ADD CARD, then click press that and get buffering to then get Apple Pay Requires iCloud Sign in to iCloud to set up Apple Pay I press OK as I have and then it bounces back to the first screen I go with 'Get Started' again? Totally flummoxed!

I just want to be able to use Apple Pay on my watch, I am signed into my iCloud account on all my devices... so just don't know where to go from here.