Train from Gatwick to Bath

The savings are considerable. The Advance tickets from Gatwick to Bath are as low as 14 GBP if you buy 2 months or so ahead. The walk-up Off Peak fare (assuming that is what you would be using) is 60.40 GBP.

That Advance ticket is so cheap I would certainly buy it now, leaving maybe 1.5 - 2 hours between scheduled arrival time and the train departure. The risk of not making the train is pretty small, but even if you do, you are only out 14 pounds.

You can use the national rail journey planner to price Advance tickets – advantage cheap, disadvantage no flexibility.

Alternatively, you can look at the cost of off-peak tickets – that’s the walk-up fare outside rush hours - £60.40 with one change at Reading.

Look at buying two tickets: Gatwick to Reading, then Reading to Bath; might work out cheaper.

http://www.nationalrail.co.uk/

Give yourself 3 hours to make the train of you buy a ticket in advance

Thanks for the input! I went ahead and booked my train. It leaves from Gatwick a little later than I'd hoped, but at least I have some leeway if my flight is delayed. And it was half the price of leaving 45 min earlier.

If you have already booked the flight and the train, then this information will be too late, but it might help others.
The better route between Madrid and Bath is to fly via Bristol. Flight times and prices will be similar to those to Gatwick. There is a regular and frequent bus between Bristol Airport and Bath and no need to book in advance. The bus fare is a lot less than the train.
Bristol is just one of the U. K. regional airports with good flight connections to places all over Europe.

Thanks for that information Bob. I had originally planned to start the England part of my trip in London, thus the already purchased flight to Gatwick.