Dear team,
I have some IR panels at the ceiling of my living room which I don’t use for electricity cost reasons.
I am on Octopus Agile (UK).
What kind of switch would I need to get Home Assistant to start them when the price of electricity is <x?
Thanks
See pics of current switches:
You actually mean infrared with IR, right?
The, an IR blaster?
I have the broadlink RM4C mini
For heating? Probably a simple relay thingy like a shelly should do the trick. 
But before getting any qualified answer you should deliver some specs of your system like maximum power draw and schematics 
EDIT: Your Horstmann E15 thing looks just like simple timer with 13A/3kW rating 
https://www.amazon.co.uk/Horstmann-E15-Electrisaver-Electronic-Button/dp/B004NOXOMK
Sorry for the lack of information in my initial post. I meant heating IR panels.
Would this Shelly product suit or would a Zigbee product be preferable?
Depends on the (still lacking) specifications of your heaters. Purely based on the specs of your horseman Horstmann it likes like the shelly could be a drop-in replacement indeed. 
Depending on your wiring/schematics (also lacking) their might be actually better solutions (which doesn’t need one dedicated device per heating IR panel for example) 
Depends on your needs and infrastructure. I would always prefer a device which allows local control and full ownership including extending/changing function on the device. To my knowledge zigbee device don’t allow ownership/control over the soft/firmware so functions can be always limited and updates depending purely on the goodwill of the manufacture. Shelly wifi devices are usally based around espressif esp chips which allow to role your own firmware like esphome or tasmota on it. You are not depend on the manufacture of the device for updates and can fix or extend functionalities as you wish 
