The TFL journey planner reckons on 1hr 5mins from Amersham to Bank.
How far do you have at the start & end of that journey?
I went to uni in Uxbridge & some of the time I was there I spent commuting from Wembley to Uxbridge on the Met line, which is quite a bit shorter.
A mate of mine lived in Amersham for quite a few years, so I am familiar with the line out that way – it is quite a long slog.
It would be a bit of a chore in my opinion, but saying that in the last 6 or so years I have had a 120 mile round trip commute by car & currently 80 mile round trip by car – so I don’t exactly make it easy for myself.
I would think that so long as you keep yourself occupied on the train, it wouldn’t be too bad. Would you be able to do any work on the train, or perhaps work from home for one day/week?
Have you looked at the cost of a season ticket? The Dad of the friend I mentioned above worked in a book shop on Baker st, so commuted from Amersham everyday. I think his annual rail ticket was about £3500 and that was years ago.