Yes, you can't pick up national rail tickets at Heathrow

So I would just book from Liverpool Street to Norwich and use an oyster card to get from Heathrow to Liverpool Street where you can pick up your train ticket (take tube and change at Holborn, don't bother with the overpriced Heathrow Express)

Another option is to take a National Express coach from Heathrow to Norwich - not sure how frequently they go and so whether the times link up with your flight but it will be nice and simple, save the hassle of the tube/central London etc with luggage, and probably not that much difference in time

Posted By: s10 yellow, Sep 25, 11:26:15