I went ahead and bought some heated gloves, which were actually cheaper than the cycling gloves I usually use. Went to Maplin to buy the medium ones, but they only had small so I got that instead. First time I tried it on I thought there was no way I could operate the switches, but after 15 mins I got used to it and had no problem.
Unfortunately I think only the palm is heated, however even without switching it on the difference from my normal gloves was amazing. Went out in temperature just below freezing for 45 minutes with it switched on and only one finger was cold, on the way back I had them off and my hands were slightly cold at the end, but not painfully frozen like before so I'm very happy with the purchase. Need to get a set of 6 AAA batteries (3 in each glove) plus charger as the batteries only last for 1 hour and could work out very expensive in the short run. Would love something better, i.e waterproof, less bulky and with rechargeable battery, but it would cost 10 times more than my £12.99 Maplin gloves!