Originally Posted by BigLar
If I do it this way, I'll probably just do LGW -> Gatwick Express (Victoria) -> taxi -> Waterloo -> Eurostar -> Paris. Since it's a holiday trip, I'll schedule plenty of time for lollygagging, missed connections, grabbing a coffee and a smoke, etc.
If there are several of you and you're willing to trade less than an hour of your time for money and doing this route anyway, NationalExpress coach service runs around once per hour from Gatwick South terminal to Victoria Coach station (2 blocks from Victoria Train station). You can catch a cab from the Victoria Coach station to Waterloo for about the same fare as Victoria train station.
Free porter service is advertised on the Express, but if it's busy you may not find anyone to help you schlep your luggage on/off the train, so you may as well pay under 7 pounds pp for a 1 hour 20 min coach ride vs. a 35 min train costing 14 pounds pp. Unless you desire a 4 hour ride to London via Brighton, be sure you catch a direct coach.