Splitting audio out for Headphones from a TV to Soundbar HDMI

[BiggusDickus]

So with my old setup, i had a TV and soundbar; the connection was from the TV headphone out to the soundbar audio in via a 3.5 mm audio jack - it was a simple stereo setup - i then inserted a switchable audio box inbetween the units and connected my cordless headphones via another 3.5 mm jack, so basically via the switch i could channel the TV sound to the soundbar or my headphones ...

My new set up today consists of a new TV and Dolby Atmos soundbar, connected via an HDMI ARC/eARC connection. I'd like to connect my old headphones via the 3.5mm jack, so again i would like some kind of switch between the TV and the Soundbar to switch the outputs, but as its HDMi, i'm a little unsure if I can do it. Does anyone have anu ideas please? Im in the UK.