yes you're quite right. I will be coming back to UK membership as well - and you can keep your vouchers for 2 years before converting to BA miles

something else I realised - you can be tesco premium customer for 1 out of every 8 quarters and convert all your miles during that period. That means you get double conversion rate without having to spend £60 every week throughout the year.

I have asked the clubcard helpline, and they say it is perfectly acceptable - not a scam or anyhthing like that