This thread begins with a overview of London Gatwick's departure lounges. You can book your spot ahead of time via the Gatwick website or via Executive Lounges, Holiday Extras, or No1 Lounges websites. It is worth comparing the results of each booking channel as prices and stay durations can vary from one to the next. Some channels such as No1 bundle in fast track security. The prices indicated below are based on adult rates quoted by the Gatwick website. Discounts for children, aged 2 to 11 and senior citizens may also be available.
Legend:
DP = DragonPass accepted
EL = Executive Lounge (Swissport) accepted
PP = Priority Pass accepted
£ = single visit pre-booking service available (and recommended)
Opening hours subject to change (times correct as of January 2018)
Gatwick South Terminal
Club Aspire

Airside, mezzanine level. Open 05:00 to 21:00
£27.50 when booked in advance (£24.50 Senior citizens aged 65+, £19.50 Child aged 2-11)
DragonPass and Priority Pass accepted
My Lounge

Airside, mezzanine level. Open 04:30 to 22:00
£24.00 when booked in advance
DragonPass and Priority Pass accepted
No1 Clubrooms

Airside, mezzanine level. Open 05:30 to 20:00
£38.00 when booked in advance or £50.00 at the door
No1 Lounge

Airside, entrance between Dixons and JD Sports. Open 04:00 to 22:00
£32.00 when booked in advance or £40.00 at the door
American Express Platinum, DragonPass and Priority Pass accepted
Gatwick North Terminal
Club Aspire Lounge

Airside lounge pavilion. Open 04:30 to 20:45
£24.99 when booked in advance
American Express Platinum, DragonPass, Executive Lounges and Priority Pass accepted (no pre-booking)
My Lounge

Airside lounge pavilion. Open 04:30 to 14:00 (06:30 to 20:00 during summer schedule)
£24.00 when booked in advance
American Express Platinum, DragonPass and Priority Pass accepted
No1 Clubrooms

Airside lounge pavilion. Open 06:30 to 15:00 (until 18:00 during summer schedule)
£38.00 when booked in advance or £50.00 at the door
No1 Lounge

Airside lounge pavilion. Open 04:00 to 22:00
£32.00 when booked in advance or £40.00 at the door
American Express Platinum, DragonPass and Priority Pass accepted