This isn't on HFP yet as far as I know, but came from the avios website, so pukka. 500 free avios available for downloading an app and linking it to an avios account

https://www.avios.com/gb/en_gb/collect/bud

It's a bit clunky, but you set an account up on the PC, download the app, log into the account and attach your avios. Seems possibly a useful app actually, though although I added Amex it doesn't seem to know about second cards etc.