David Ward -
http://www.into-the-light.com/
An absolute visionary in my mind and leagues ahead of nearly every other landscape photographer working (again, in my opinion).
If I meet any naysayers of photography as an art form, David Ward's work is often the first port of call.
His photographs might not strike you straight away, but take a little time to absorb the images in his gallery.
Simple, beautiful work. You'll learn a lot from his blog too, which often attracts the input of academics and mathematicians!
Enlightening reading on our art form and it has really paved the way for my thinking and practice.
I dare say the best landscape photography teacher since Minor White.
Paul Wakefield -
http://www.paulwakefield.co.uk/
Just stunning work. Nothing more to be said.
Andrew Nadolski -
http://www.nadolski.com
He hasn't produced any other notable work since 2005, but his 'End of the Land' series is a high benchmark in contemporary landscape photography.
I have the book and can tell you it's well worth purchasing - that is, if you're interested in landscape photography as an expressive art form.
You might also benefit from subscribing to LandscapeGB -
http://www.landscapegb.com. Perhaps concentrated a little too much on the technical, but I've made a few discoveries from the mag and I consider myself fairly well informed in regards to the landscape 'scene'.
As someone else mentioned; John Blakemore. He is the father of fine art landscape photography in Britain (although working in relative obscurity) and his retrospective has recently been published.
A good starting point and he is still working, to the best of my knowledge.
Apposite to what others have said, the 'imitate, assimilate, innovate' idea is something I live by.
Currently working on innovation!