On most good gliding days, long cross country flights are flown from the London Gliding Club. These range in size from 50 miles up to over 500 miles!
On weekends there is a task briefing covering the weather, airspace, and three tasks of varying difficulty. Pilots choose which one they want to fly, program it into their flight computers (so they don't get lost) and set off. Sometimes this is an informal race, but more often than not it's a chance to fly side by side with your friends.
Cross country pilots get better with practice and training. The satisfaction of reading and beating the weather, and achieving your own personal best is immense.
The British Gliding Association has a online competition called the BGA Ladder. This allows glider pilots to record how far and fast they flew, and compare their flights to other pilots. At the end of the year prizes are awarded for the best flights and pilots.