From Heathrow: Railair Link Coach to Reading every 30 minutes (50 minute journey). There are trains approximately every 30 minutes from Reading Central Station to Bristol (80 minute journey). By coach from Reading to Bristol (approximately 90 minute journey)
From Gatwick: By train: Gatwick to London Victoria every 15 minutes (30 minute journey); from Victoria by underground train or taxi to Paddington. There are trains from Paddington to Bristol every 60 minutes (1 hour 45 minute journey)
From London Victoria / St.Pancras (Eurostar): By train: By underground train or taxi to Paddington. There are trains from Paddington to Bristol every 60 minutes (1 hour 45 minute journey). By coach: Victoria coach station to Bristol every 60 to 120 minutes (approximately 3 hour journey)