Just a word of caution. Avanti and weekend trains are not a good combination. They don't seem to have enough train crew and depend on overtime and "rest day" working. Those rely on goodwill of the crew but industrial relations at Avanti are below the floor, so lots of crew are not willing to volunteer. The point I am trying to make is that cancellations at weekends are a big problem. On one recent weekend, Avanti had to cancel 60 of their planned services. If you could travel on Friday instead, I would.