I think THPP is pretty much spot on, in my situation anyway.
The last direct train for me back to Victoria is the 22:40 from Lewes. For the Forest game it seemed a bit touch and go whether we'd make it but we just did and got home to Bromley at around 00:15.
I left on the final whistle Tuesday, looked at the queues on the ramps for the eastbound trains and walked straight to the westbound platform. I was on a train to Brighton by 21:57, walked off the train and just managed to get on the 22:02 Thameslink to Bedford and, because it was just one of those nights when everything worked out well with connections, I was home in Bromley at 23:17 a whole hour earlier than if I had taken the Lewes train. I don't think I could have got back to a parked car and driven home quicker than that.
Even if it didn't work out quite so well there were just so many more options back to London from Brighton so that's what I'll be doing in future.
Why would you ever go to Lewes in the first place? There is literally no reason I can think of post match why you would head to Lewes to then go to London.