Redhill Aviation used to move part of their operations to Shoreham perhaps they still do but as far as the airfield not turning to mud anymore, well who knows....
Although I have never flown from Shoreham I have stopped there a few times and always thought it was a lovely airfield with plenty of character (with a licenced pub too
).
From Croydon it is probably a bit far so BIG seems like a good possibility with an approach and a beacon on the field which saves time when practicing instrument flying.
Don't have a Kiwi girlfriend but if she is made of the same stuff my Kiwi mates are made of then beer (plenty)and sambuca (preferably alight) should do the trick.
Good Luck