@AxLED - thanks 
The playlist route actually worked better, as I can also use the next/previous keys on the remote to switch between stations, rather than going the original route I was thinking to have preset “favourite” keys for each individual station.
But I’ll certainly make a note of your method too for future use in case I do want to go that way for specific stations in the future. It’s all working nicely though, routing stuff via Home Assistant and using some Ikea Tradfri remotes to control my Volumio Pi’s.