Seems many people are asking the same question without answers.
Barclays indeed didn't sign off on the use of Thier cards on Google play. Now they are fully in. I have my Barclays card in my Google wallet on my phone, but Garmin Connect seems to be well behind the curve.
Could I please get an answer to what is being done to remedy this situation?
Looking at the list on Garmin's help site, supported banks in the UK, seems that there are only 5 or 6 in the list. One of which is a UK bank, one is Revolute, and the others I have never seen on any high street in the UK. Garmin get with the times.