Visited Holbeach once a few years back and that too is used more by USAF units than RAF.
Had the pleasure of watching a pair of A10s over from Germany usng the range; apparently they don't book in advance they just call up on the offchance there's a slot available.
Gone are the days of streams of RAF Harriers and Jaguars on the range; I suppose it's just Typhoons and F35s nowadays.