For anyone wanting to try Tanith Lee's fiction before they buy, a few of her short stories are available legally as online free reads and podcasts from various magazines' websites such as
Lightspeed and
Weird Tales, listed here at
her entry on the Free Speculative Fiction Online Website.
Looks like it's mainly the gothic horror-ish/dark fantasy stuff which seems to characterize her later work (she wrote in a very broad variety of subsubgenres over the decades), but it should be a good starter to see if you're interested in reading more.