LlaniDavis is right but some portable televisions can be operated by either 240 volt mains or 12 volt power and probably cheaper than a 12 volt operated only but you will need the appropriate 12 volt adapter lead. If you check the model number of the TV first you can then search for the required adapter.
Back in 2011 I bought a 240 volt Alba combi TV/DVD for £90 from Argos and when I read the instructions I found by accident that the TV can also be operated by 12 volts (cable not supplied). I searched online and managed to get the compatible adapter lead from Maplins for under a tenner so you just need to check the appliance information first as you could use the TV both at home and in the caravan.
Agree that for ease of use a 12V TV is ideal, but I recently bought a 19" Samsung LED TV that runs at about 17W. I have a 300W invertor that claims to run at 94% efficiency so the current draw is still only about 20W.
Great TV too, with a very wide viewing angle (important in a caravan). My previous 12V TV had a terrible viewing angle, you had to be sat straight in front with exactly the right tilt.
i have the same Alba tv as Tango from argos, i made up the lead from an old charger lead and the 12v plug to suit the socket next to the aerial socket (these can be bought from towsure etc..). it seems to work ok but there is a time delay between pressing the remote control buttons and the tv reacting to it.
if you buy caravan/motorhome specific tv's they are crazy money. i just bought one from maplin because a wanted a 22" screen, 12v operation and an inbuilt Satellite receiver it cost £220! the picture seems to be no better than the Alba BTW.
my current van has 2 aerial sockets so the Alba TV is for the kids end of the caravan.
------------- First van bailey ranger 550/6
Now the proud owner of a coachman amara
A large number of tv's run on 12/15 volt even for home use
the 13 amp socket is usually a transformer for either 12 volt or 15 volt on tv's under 32 inch.
I have two one in bedroom at home and one in van which need 240volt supply which is then transformed into 15 volts in the van which gives an excellent picture as well as all free view stations and plays cd's and can be used as pc if site has wifi,
That is if wife is not watching 4 in a bed or corrie, enerdale.or come dine with me.
The choice of TV depends on what you want to watch. No one has mentioned Avtex TVs.Now these have a high price,but are light, built for the caravan,camping,boat market and have a wide viewing angle, operating on 12 or 230v. They also have built in DVD player, Freeview and Freesat,which means no extra boxes to buy or cables all over the place
The roof aerial should work OK. Is it s round one with a spike on top. If so that is a unidirectional one. There will be an amplifier in a locker near the aerial. This has a switch on t to switch it on and boost control switch. Make sure its switched on and try thee boost control for the best picture.
If it's not a round one but slightly pointed towards one end it is a directional one. There will be a tube in a locker under it. You raise it up and rotate it so it points at the transmitter. Again there will be an amplifier as for the non directional one above.