THE NEW Great Britain Passenger Railway Timetable (pounds 7) comes into effect tomorrow, and is likely to be the last covering the unified rail network. Apart from the expected withdrawal of some holiday trains, there are few changes to the summer timetable. One innovation is adding trains from Swansea, Cardiff and Bristol direct to Waterloo, for easy connections to Eurostar trains through the Channel Tunnel. Table 350 ('London Waterloo and Paris/Brussels'), however, is blank]