That would be my recommendation. As with all things in this area, it's a matter of opinion and there are those who will suggest that you sell the kids, go on the game and re-mortgage the house to buy a Sennheiser mkh60 microphone for £1500 but, for what you're doing, the at897 will do the job admirably. It will also outlast your camcorder!
It's worth taking a bit of time to play with the mic and find out what it does and what its weaknesses are but it will still sound much, much better than your camera's in-built mic.
As for the stereo vs mono arguement... top quality mono sounds better than poor stereo every time.
Have a look at the prices from
www.thomann.de before buying. I can heartily recommend them for price and service.