I was looking into getting tickets to watch Wales vs Japan in Pool B. I would have loved to have gone and watched Wales against Australia, but can’t really afford it.

Any way, luckily I looked into train tickets to get to Cardiff Central from London, before I purchased the ticket, since by the time the game has finished the train home would take 7 1/2 hours..

Well since you ask, the route they suggest is

Depart: 22:00 Cardiff Central (CDF)
Arrive: 23:00 Bristol Temple Meads (BRI)

Depart: 23:44 Bristol Temple Meads (BRI)
Arrive: 00:39 Taunton (TAU)

Depart: 02:47 Taunton (TAU)
Arrive: 05:24 London Paddington (PAD)

So it looks like I will have to watch the rugby on television like everyone else..