Yes you can adjust the lip sync.
Assuming you have a Humax HDR,on the remote press menu then scroll down to "settings" and press ok, scroll down to "tv set up" and press ok,scroll down to "lip sync" and press ok then use left/right arrows to adjust the time delay,then press back up to finish.The time delay should now be applied, AFAIK it will change the delay for all channels though so you may need to re-adjust when not watching ITV HD!
If you have an A/V receiver you should be able to apply delay's on that also if need be,