Hi:
I take it you live in the US or Canada and not the UK?
If I am right you need to buy a step up convertor. The type you will need is dependent on the Wattage of the TV. To check this out you need to look at the lable on the back of the Avant. Once you have this information you need to go to Tandy/Radio Shack and buy a step up transformer (with a socket for a UK plug like the one pictured).
I would always buy one that is slightly more powerful than what you need rather than just within the limits as the de-guass coil in the Avant will possibly make the fuse blow on something that is barely capable of handling the power. Also buy a few spare fuses when you buy the transformer.
There is a company in the UK that sells them. However they are heavy and the cost of shipping will be prohibitive I think:
http://www.newmarket-transformers.co.uk/step-up-transformers.asp
Another US company I have heard mentioned in a forum that will sell them is Newey and Eyres.
Hope this helps.
Graham