First the very limited good news. It's summer. It might not look much like it but you have three things going for you that we didn't in the winter. Temperatures are higher, the sun is going to evaporate lots of water and transpiration is working at the maximum, so trees and plant life are going to remove lots more to the atmosphere.
  Grass is amazing stuff, with fantastic powers of recovery. We had a lake, 7' deep in the middle, covering our ground for 4 months. When we got the last of the water off the square, the whole ground looked like the Somme, but after just 4 days of sunshine and warm breezes, the eye of faith could see a green cricket ground again. The picture of the ride-on mower here was taken just over a week after the pictures of the square on the left.
  Now the bad news. There is nothing you can do while the water is not receding. Don't waste money fighting nature. We did. It just created more frustration. You can use the time to prepare by locating and borrowing what you're going to need.
  If you're in a dip or a bowl, you'll need a pump to get rid of the remaining water. Find your local branch of Andrews Sykes, listen to their advice, and get a big one - a 3" submersible drainer if they can manage it. You'll need somewhere to pump it to and you won't be able to run hoses across roads. You'll need to put the pump input at a low point and you may need to dig a chamber and a trench to create one. You may need to secure it if it is to run overnight. Pumps are temptingly useful in flooded areas.
  You'll need a water hog to remove water you cannot pump away because the pools are too shallow. You'll need squeegees and lots of buckets and pairs of hands to get it off the square. Just close your eyes and get rid of the water. And you'll need to read this.
  You may need to dig some small trenches to get the last of the water away. You can fill them in again when it's dry.
  If it's in the pavilion, don’t pump it out with a pump powered by an internal combustion engine. They’re for outside use. You can locate them outside and then run your hose input inside the building.You'll need to dehumidify the whole interior before starting renovations. A dehumidifier's efficiency increases exponentially with temperature so it will be cheaper and quicker to hire heaters as well. These must not be combustion-based heaters, which just add more moisture. You need radiant heat from electric fires.
  Don't assume that anything is unrecoverable just because it's been under water. Our chipboard pool table was fully submerged for 4 months but was OK. However, the glue in the joints of all our wooden furniture dissolved. The numerators for the scorebox looked shot but a clean up and some WD 40 did wonders.
   The mowers were fine but remember, water is not a compressible fluid. If you try and start a 4-stroke engine with water in its cylinders you're going to break it, so be very sure you've cleaned it all out.

Tea, sympathy and understanding employers are very important. Get your insurers on the job early, keep them onside but remember it's a loss adjuster's job to minimize your claim, not yours. Get your volunteer workers organised. You're going to need lots. They want to start playing again, don't they?

Talk to your County Board and make them worry about your problem. They can help with kit from unflooded clubs. Worcestershire (forgetting this season) have played in a matter of days after being flooded.

Our flood diary, a 28 Mb pdf, which has photos of what we did and extracts from the website is here, and you can see more photos from that winter here.