Late fare pricing

I am planning to book for LGW to Jamaica return to leave in 4-5 weeks time. What is the pricing pattern for booking in that time frame, do prices generally go up or down or stay same? I know there is the risk of leaving it late and finding flight fully booked.

[Neil]

The later you leave it the more expensive it will become. Most of the cheapest fare buckets have advance purchase restrictions, so the sooner the better.

Thanks for the advice.