ISTR about £4-5 when I stayed there a while back.
There is a free local bus zone around LGW. Finding the local buses is a pain unless you know where you are going, and I suspect that the hotel is just a little bit too far off the airport to fall within the zone, or be on the route of any of the frequent buses. There is a slim chance that the Horley buses go that way since they go through Povey Cross - you'll need someone with more local knowledge. Whenever I use the buses, I'm going off to the dear old CAA at Aviation House.
Bus routes are at
http://www.gatwickairport.com/assets...trobus_map.pdf and more details of local buses are at
http://www.gatwickairport.com/portal...0357e120a____/
To get to the local bus stops from LGW south, head for international arrivals, walk past this on your left, towards left luggage. There's a small door off to the left at the back of the seating area (same side as arrivals come out of, but beyond there, and it used to be signed something like 'Local buses' but I think that had changed the last time I used it) which leads out to some lifts and stairs which go down to the ground floor, and from there you access out onto the perimeter road and the bus stops. It doesn't look like a public access, because it's mainly used by staff, but it is. And although I've used it, I just cannot remember where the local bus exit is from North.