Hard to tell from just pictures, but it would appear you just need a simple rocker switch, mains rated. The crucial thing will be the size-for-size match more than anything, so as long as thats the same physical size it looks good to me
Has to be mechanically equivalent (SPST, DPST or whatever and, as Steve says, the correct dimensions) with the same or greater electrical ratings - if it's a 240V/5A switch fit at least a 240V/5A switch.
You can generally pick something up almost identical. If it's a push-fit, sometimes they can be a mm or so bigger if the original was best quality American Imperial Chinesium but a couple of wipes with a file on the edges of the mounting hole will usually sort that problem out.