The costs can be computed based on this PDF table (permanent link in case of update) or using the Single Fare Finder.
With an Oyster card, a journey from Waterloo to Clapham Junction (zone 2) costs £2.20. From Waterloo to zone 3, you would pay £2.70 (all off-peak fares). If you plan several journeys within zone 1-3 on Saturday, you would pay £7.70 in total. For Surbiton, the Fare Finder and the table don't seem to agree, so I am not sure how much it would actually cost.