Thanks for your reply - I will take a further look into that. It's such a shame Avios can't be used for spending at all those retailers. I have never been bothered with collecting small amounts of Avios from retail shopping (albeit perhaps it would have added up to substantial amounts over time). So I hadn't even thought of this route to triggering an Avios earn.

I will certainly look at this. I'd love to also know the answer to the question about flight redemptions if anyone does know !