Hi nickyj, I tend to catch a train to London Bridge between 8.10-8.30. I rarely get a seat, but it's such a short journey to LB, that as said above, even if it's really crowded, it's bearable. Two of the trains that I normally catch keep getting delayed recently, but hopefully that will be short-lived.
In terms of coming home late after a night out, I always catch the 176 bus. (Just because it takes me to the end of my road and I feel safer going that way). It's a good regular 24 hour service, that you can catch from most central bits of London (Trafalgar Square/Waterloo/Oxford St/Tottenham Court Rd etc.) Worth having as a back up if there are train problems.