In my experience hotel WiFi often isn't fast enough or stable enough to stream iptv, but you don't say whether you're holidaying overseas or in the UK. Also, some hotels have TVs without access to a hdmi port due do how close they're mounted to the wall or sometimes the tv is behind a mirror.
The app will be provider dependent, and if his customers are generally happy with it then it should be OK for the duration of a holiday. I'm guessing you usually use an enigma2 device or something?
I usually take a tablet or a laptop abroad as it's just a matter of connecting it to the hotel WiFi/local sim card hotspot and away you go.