Wireless headphones are available. From cheap and nasty up to WTF! prices

Only potential problem is the base unit will need mains power. So that may be a factor, but if you can overcome that then they will plug into the headphone jack just like corded headphones.
Of course if the headphones mute the TV speakers when plugged in that could be a pain if you do both want to listen. You could drive two sets of wireless headphones from the same base unit but a bit anti social (or not as the case may be

). Otherwise you may need to find an alternative audio output. If not a set of phono sockets then perhaps a SCART socket and adapter.
The wireless headphones will work with such outputs just as well as from a headphone jack so no issue there. And they should have volume controls on the headphones so having a fixed level output from the TV SCART/phonos is not an issue either.
Personally I have a soft spot for Sennheiser. never heard a bad pair from them. Though they are not the cheapest wireless devices you can get. For example
http://www.amazon.co.uk/Sennheiser-W.../dp/B005SO0OD6