You can get National Rail fares from nationalrail.co.uk and Oyster or contactless fares from my fare finder. For Underground stations within zone 1 you can put the name into National Rail and it will offer you the through ticket price. It’s the same price to any zone 1 Underground station.
Now for the fun. From Virginia Water you can go either way to get to Waterloo; via Richmond is normally quickest, but if there’s a through train via Weybridge that can also work. If you’re using the through ticket to either Underground station you’re probably best off changing at Vauxhall. From there it’s the Victoria line to Green Park, or change at Victoria for South Kensington. If you want to mix tickets with Oyster PAYG then you can also change at Richmond, Putney (for East Putney), or Wimbledon (if you’ve gone via Weybridge). All three offer direct District trains to South Kensington and you can change to the Piccadilly at either Hammersmith or Earls Court for Green Park.
Fare combinations are:
Virginia Water to zone 1 Undergroud station (through ticket): £29.60 return
Virginia Water to Vauxhall £23.60 return plus 2x £2.80 PAYG: £29.20
Virginia Water to Putney £19.20 return plus 2x £3.40 PAYG: £26.00 (includes 7 minute walk Putney to East Putney).
Virginia Water to Wimbledon £17.90 return plus 2x £3.70 PAYG: £25.30
Virginia Water to Richmond £15.60 return plus 2x £4.40 PAYG: £24.40
Hope that gives you some help.