In reply to MattJP:
Late reply so not sure if you still need any info, but I'm 4' 11" and have the same inside leg as your missus.
What kind of cycling trews are you after?
I wear 3/4s (tight ones, and overshorts if mtbing) if it's not too cold as these usually fit without problems, just be careful if the ones you look at have an articulated knee as that might be in the wrong place.
For cold weather, I've tried Gore winter tights - faaaar too long, but with overshoes, you can hide the horrible wrinkles at the ankle! I've also got Rapha winter tights which aren't padded so you can wear them over shorts or 3/4s. These are absolutely perfect leg length wise, but incredibly expensive (I got mine for a fraction of the price at the first ever sample sale they had in Manchester, lucky day!)
Hope that helps!
K