Only allowed if your wife is undergoing training.
From the ANO:
Members of flight crew requirement for licence
21(1) Subject to the provisions of this article, a person shall not act as a member of the flight crew of an aircraft registered in the United Kingdom unless he is the holder of
an appropriate licence granted or rendered valid under this Order.
(2) A person may within the United Kingdom, the Channel Islands, and the Isle of Man without being the holder of such a licence: act as a flight radiotelephony operator if (a)
...
(ii) he does so as a person being trained in an aircraft registered in the United Kingdom to perform duties as a member of the flight crew of an aircraft;
(aa) he is authorised to operate the radiotelephony station by the holder of the licence granted in respect of that station under any enactment;
(bb) messages are transmitted only for the purposes of instruction, or of the safety or navigation of the aircraft;
(cc) messages are transmitted only on a frequency exceeding 60 MHz assigned by the CAA for the purposes of this sub-paragraph;
(dd) the operation of the transmitter requires the use only of external switches; and
(ee) the stability of the frequency radiated is maintained automatically by the transmitter;