The Freeview boxes are for those wi annalogue tv's and if he has a look here, http://www.freeview.co.uk/home he can put in his postcode to see what like reception he'll get.
Depending on where he lives, he may also need to swap his present aerial for a wideband version and possibly higher gain - digital TV requires higher signal strengths than terrestrial. As suggested by corbyloo, use the postcode checker to see if he lives within range of a FV transmitter.