I don't think 30-40 minutes is feasible from Richmond or Chiswick. MAYBE if your timing was impeccable. And that assumes you live practically across from the origin station and the workplace is practically across from the destination station. And all the lines are running perfectly. And the sun is the right kind of sun.
Most Londoners have commutes of 1.5 to 2 hours due to getting to the station (e.g. walk, bus), waiting and switching (e.g. some lines are a good 10-15 walk from each other at interchange stations), and getting to work from the destination station (e.g. more walking and/or busing). I'm at 1.5 hours even though I live technically "close" to work because I have to bus/walk to the station, get a train in, bus closer to work, and walk from the bus stop to work. Plus all the time waiting for the next train or bus at each change over. And during rush hour, you might have to wait for several trains (or buses) before one stops at the station that is empty enough for you to be able to squeeze on. Sadly, just because a train arrives at a station, doesn't always mean you can physically fit on it if it's already jammed full of people.
I don't want to be negative, but I only know a handful of people with door-to-door commutes in London of 30-40 minutes, and they are all within walking or cycling distance of their job.
I suspect you'll either have to decide if you want the neighbourhood or the commute.
I love London. But the commute can be awful.