There were the same engineering works for Norwich game, and I had no issues and bus replacement service was really good with plenty of coaches available.
plenty of trains back to Liverpool st after the game 19.41, 19.52 and 20.10, with journey taking around 2 hours 10ish, but found on way back from Norwich you could even make earlier trains back from Billericay, so should be back at Liverpool St by 10.30pm at latest