Caravan/morohome home network for phone to TV

Now that Iplayer is stopping the computer app for downloading programs to my lap top for use on holiday I need a way to link / cast my mobile to the TV. It will still be possible to download programs to a mobile.

I have already a google chrome cast deice which works well when put in a TV but it relies on a wi fi network. Fine at home but I need to create a caravan / motorhome network that will use mobile data by mistake!

Is it possible to use a normal house router to connect the phone and TV with the internet switched off (mobile data on phone)?

I tried using the phone as a hot spot but this does not work without going to data use.

Anyone done this already?