Seems reasonable. Assuming you don’t want to arrive bang on ko, it could easily take well over an hour during a Friday rush hour. When you have to negotiate Reading traffic, then the Marlow bypass, then Wycombe it’s a horrid journey. Check out how long it would take by train !
Remember going to watch Reading at Adams Park years ago on a Tuesday night. Missed the kick off because traffic was horrendous and couldn't find a parking space. So it probably does take longer than you think.