Question about trains running from Gatwick Airpot to London city. I'll be arriving at Gatwick airport on the 21st next week. I've read that Southern Rail and Thameslink are cheaper alternatives than taking the Gatwick Express. But when I compared prices online from Gatwick to Marylebone, Southern and Thameslink cost around 14GBP which is only a few dollars less than Gatwick Express which cost 17GBP.

What is my cheapest option to get to Marylebone station from Gatwick airport? I'll also be arriving in the morning (around 9am I think)

Thanks
