When I first bought return J tickets on CI to Gatwick, the CI website said there was no lounge in Gatwick.
We had a 9pm-ish flight, checkout in London was around 10am, allegedly no lounge at the airport; so I booked a room at the hotel attached to the airport (a Hilton?).
By the time we flew there was a lounge available, but the UK had a few days in a row with (gasp) over 30 degree heat so they had train delays; we therefore went to the airport ASAP, and having a hotel room in which to have an arvo nap & kill some time without dealing with a billionty people or inadequate aircon made a very comfy & worthwhile ending to our holiday.
Would book again!