Originally Posted by
Allie Abby
ok tks for info ,if no diff in price , ill just buy return tixs when I get to Gatwick then , thought buying ahead of time be cheaper
The cheaper tickets that are available if you buy ahead of time are called "Advance" tickets - these are limited in number, and there are normally different tiers of prices for them (cheapest tier, second cheapest and so on).
For flexible (Anytime) and semi-flexible (Off-peak) tickets there's no saving to be made by buying them ahead of time.
(OK, there are occasionally special offers when buying Off-peak tickets from the train company's website, but this is the exception rather than the rule.)
National Rail webpage explaining the different ticket types (Advance, Anytoime, Off-peak etc)