Fat Duck isn't open on Mondays. The pub is the Hind's Head (which is great), and there's the Waterside in, which I think is also closed on a Mon.

If you do end up staying in the airport, Heathrow has a lounge which is available to all who want to pay the fee. I can't remember its name, but I found out about it on the Heathrow site and I asked about it in the Airlines site here sometime in 2005.

The long layover should be considered an adventure, not an inconvience.

My folks always go somewhere between flights in London. They actually plan it that way. They prefer to grab a cab after stashing bags, but for my $$, I do the Tube. There's never any traffic to worry about, no getting lost etc.

Windsor is lovely, Kew Gardens is amazing, and Hampton Court has a nice maze...

Whatever you do, it will make you feel relaxed, refreshed, and ready for the next leg of your journey. I find getting out into the fresh air and sunshine the perfect way to get you ready for a nice nap in the plane.

It really is only an hour and a half early in London- but maybe you can check in when you get there and then head out.

Have an amazing adventure- and please post to let us all know how it went.