I got this journey from TravelLine -
http://www.traveline.info/
08:48 From the centre of Kingston-upon-Thames (London) walk for about 6 mins
0854 Kingston Upon Thames, Eden Street (KT1), Stop D1 (on EDEN STREET)
Take Metrobus Bus 465 towards Dorking, Rose Hill and get off at
0951 Dorking, Moores Road, Stop H (on High Street)
Then transfer to
1012 Dorking, Moores Road, Stop H (on High Street)
Take Metrobus Bus 93
towards Horsham (W Sussex), Bus Station
and get off at
1101 Horsham, adj Bus Station (on Bus Terminus)
Then transfer to
1130 Horsham, Bus Station, Bay E (on Bus Terminus)
Take Stagecoach South Bus 17 towards Brighton (Brighton & Hove), Imperial Arcade
and get off at
1240 Brighton, Old Steine north, Stop H (on Old Steine)
Then walk for about 4 mins to the centre of Brighton (Brighton & Hove)
1244 Brighton (Brighton & Hove)
But other start times would involve different routes. I suggest you use TravelLine to find the journey that suits you. Enter your start and finish locations, date and time you want tto start and uncheck all moodes except "Bus".