Hmmm, T400CN is said to have lower contrast than ordinary B/W films...(posted 8856 days ago)There are Efke films R25 and R50 that are made for portraits in artificial light, very fine grain, but will have normal to hard contrast if you can't controll the process yourself.
Verichrome Pan and Plus-X Prof. Are good portrait films too.
To get softer negatives the way to go in this case is to overexpose a little and underdevelop. But you say you can't do that.
I guess you'll have to use a soft filter, or a soft portrait lens. don't know if your camera brand has one. There are Zeiss Softar filters. Very expensive, but the best you can get. They give the same softness with all apertures.
My best advice: Get a darkroom to develop in!