There are many international-only gates at LGW. Only some of the doors at gate 55 are dual domestic/international.

In terms of domestic bus drop off, you used to be dropped off adjacent to the domestic baggage reclaim, however with building wokr underway at the north terminal, the drop off is exactly as described...up a long flight of stairs and then you rejoin the normal domestic exit- also disrupted somewhat by the works.

It now means that whereas bussing could be a quicker exit to landside, it is now certainly longer than exiting via airbridges.

I don't know if sunrisegirl or others know what the building work is and whether it will improve the exit routes for domestic passengers.