You could see what's blooming at Wisley in November. The great gardens that I visited in August that I'm GUESSING would still be good in November would be Hidcote in the Cotswolds (open until Nov. 7th,) and Beth Chatto's garden (open weekdays in November and closer to London than you'd think by train.)

Find the most recent edition of this book that you can: The Daily Telegraph's "The Good Gardens Guide" -- it's arranged by area which is helpful and contains accurate information, descriptions, and opinions about all the best gardens. And I think, some garden centers. Most of the gardens I just looked up for you are no longer open in November. Darn!

How about this: buy the November issue of BBC's Garden World magazine (say, at Barnes & Noble) before you go and see what it recommends, and once you get there buy other British gardening magazines.

Good luck and I hope you get to return to England during gardening season because it is truly wonderful. Let me know what you find in November.

Classes in November by one of my favorite gardeners, Sarah Raven, who wrote "The Bold and Brilliant Garden":

http://www.thecuttinggarden.com/html/courses.asp?type=gardening

Thank you, Crocosmia!! I will certainly buy the Daily Telegraph guide and the BBC Garden World magazine. I am travelling with my husband who is not a gardener, so I may not get to do everything. Your suggestions will help me find the "best of the best" which I appreciate very much.

When I went to England I was with my husband for half the time (best friend and fellow gardener for the other half.) He was just going to drive me around and then go do other things. But it took so long to find the first garden that he figured he might as well look at it -- well, he visited every garden after that (about 10) and then came home and ripped out large sections of our lawn, built a rock wall holding a raised woodland garden and another rock structure for a few dozen alpine plants. AND he keeps giving me advice about MY gardens....
Have fun!