Would Lisp be extremely difficult for a new(ish) programmer to learn?

I'd say a Lisp will be easier to learn as a new programmer than if you wait. That's because the way most languages encourage you to think about programming is a handicap to learning Lisp; being experienced with a more conventional language will probably help in some ways, but not with the qualities that make Lisp unique.

Scheme --- the Lisp with which I'm most familiar --- is probably about as easy as Python to learn, especially if you choose PLT Scheme (now renamed Racket), which offers you a lot of helpful extensions. Common Lisp is probably about the same difficulty, though I find it less instinctive for reasons which are probably not universal. I have found C much more difficult than either, for the reasons Norman Ramsey suggests.

What one I'd suggest learning depends very much on what you want to do with it. If you want to learn a crystal-clear language with no frills, whose core can be learned quickly, learn a Scheme that implements the R5RS standard, such as Scheme48. If you want a more capable Scheme, either immediately or later on, learn PLT Scheme/Racket. If you want a big, friendly, diffuse language of immense power but not as visibly internally consistent as Scheme, choose Common Lisp; Steel Bank Common Lisp is a good implementation.