It's important here to echo Scion (and others elsewhere) who have said just dive in with the Book of Thoth.
It amazes me this reputation it has got for being impenetrable. Sure it can be difficult, but with a little concentration I find it perfectly accessible taken a bit at a time. I read it a while back trying to remember everything but now I am curently going through it again. I have put my angst about writing on books to one side and am scribbling, annotating, underlining, cross references with Post-Its all the interesting things I read in it.
Honestly, if you go for the Thoth deck, get the Book of Thoth, throw caution to the wind and write whatever you want all over it, in the margins, on the flyleaves.
There are passages which are so uplifting and lucid, it really is wonderful to read and I can't imagine the deck without it. Nor should I have to!