You're also able to request a change of dates of your holiday if you prefer to travel at more suitable times -3/+14 days from your original travel dates at no additional charge/penalty. Looking at the schedule BA depart LGW to KGS at 1130hrs on Mondays, 1500hrs on Wednesdays and 1400hrs on Thursdays. You can request the changes over the phone with BA Holidays under their standard rebook policy due to the re-timing of the original flights booked if these are more suitable to your needs. Obviously if you're extending your holiday length you'd be on the hook for additional accommodation charges.

Alternatively Blacklane are within catchment for Godalming to Gatwick and while not cheap are reliable...