I'm new to LR's but 40K and starting to notice sloppy shifts sounds like a good reason to change the transmission fluid. I haven't even thought about doing this on mine yet so I'm not sure about the procedure on these but there's probably no need to go crazy with a complete flush or anything really expensive. On most cars, you can drop the pan, maybe change a filter, and put 4 or 5 quarts of new fluid in to top it off and that will usually be plenty at 40 or 50K miles to make it drive like new again.
I know just about all car makers these days don't even put a dipstick on their automatics and say their fluid is good for life but I haven't seen a car with more than 50K on it that didn't shift a little sloppy and shift a lot better with some fresh fluid in it.