Fill a water bottle with hot water and stuff it in a sock, then into the bag a few minutes before you get in yourself, it keeps warm for a few hours normally and helps you get to sleep. In the morning the water will still be lukewarm so good for a wash/shave while your heating some fresh for a brew & breakfast.
Have something fatty before getting in the bag. Stuff like pate, nuts, oils etc.. really get you generating a bit of heat. Also, don't go to bed cold. Move around a bit and warm up before getting in the bag, that way you warm it up quicker.
If its the misses then sleep close together, with the bags touching if possible to share a bit of heat, make sure you've got a decent mat and bag. Wearing a light set of thermals, along with a hat and pair of socks also makes a big difference, make sure she isn't putting her head in the bag and breathing into it. Fleece sleeping bag liners are cheap but a bit bulky, bivvy bags also warm to up the warmth of a bag even in a tent.
Just a couple of things there. I don't believe that its necessary to carry a heavy canvas tent in this country to keep warm at night, even in the winter, and that it'll double in weight if it gets soaked with water.
Tonyuk