GPS works because space-based satellites transmit time signals, allowing us to determine our relative position on Earth in three dimensions - so your GPS is sort of a TARDIS.
Note that the cache is not on the strange object that's materialised on the lawn and you don't have to enter 178A to get it (so don't stray onto private property).
You are looking for a gray-coloured Eclipse mint container, which only has room for a cache note so BYOP.
Be careful of both the reasonably busy road and the mad man with a blue box!