@craigablake
You are registered in the UK, but currently posting on the US Community boards. You might want to sign out of ebay.com and sign in to ebay.co.uk and try checking out again. If you are still unable to check out, you might want to check the UK Community boards to see if you are experiencing a UK issue:
https://community.ebay.co.uk/t5/Discussion-Boards/ct-p/13?nobounce
If you are having trouble signing in to PayPal through eBay Checkout, there are some things you might try in this thread:
https://community.ebay.com/t5/Technical-Issues/Checkout-issues-with-PayPal/m-p/30028155#M59069
The issues outlined there seems to be related to either PayPal 2-Factor Authentication, or PayPal One-Touch settings -- at least altering one of those two might serve as a workaround if you are having difficulty signing in using checkout.
If you are able to sign in to PayPal through eBay Checkout OK but the transaction is failing in some other way, it may be a different issue.
