Hi,
The voltage of the unit isn't going to be the main concern as you could get a voltage step up transformer if it's 240V only.
The main issue is what you'll use the TV for. If you are intending to watch domestic USA terrestrial broadcasts and cable/satellite TV, then the TV won't work. This is due to the Video systems differences, the USA uses the NTSC format and the UK uses PAL. There's probably a specialist unit that can convert from system to system and at high quality i.e 1080p or 4K, but it won't be cheap assuming it exists!
If you want to just play video games and use it to watch footage you shoot on a camcorder etc then you'll perhaps be ok using the HDMI input provided the camcorder/games console used is a UK PAL one.
In short, it's just not worth it to take a UK telly to the USA (nor a USA telly to the UK). Prices for large screen TV's are almost dirt cheap nowadays and a Samsung/LG/ 40 inch LED telly can be had over there for just $360 USD, and down to around $260-275 for one of the budget brands.
Cheers, DtM! West London & Slough UK!