1st advice do a lot of research before you spend any money - read lots of noob threads
most of them say to post a link to your public rack - so we can click through and help you
here it is :
to a large extent almost any modules can be used to make any type of music
however mostly when I think of ambient I think of delays and reverbs, vcas and sample and hold and to some extent granular - not really enough of these - unless you are intending to use the distings for this - in which case while disting is an excellent module - get dedicated ones of these - multiples in fact
what do you already own?
big hint - remove the semis from the rack - they already have cases and take up too much space
no where near enough utilities - more mixers (of a variety of types), vcas (I would like to be saying more vcas, but unfortunately you have not done enough research to learn the value of vcas yet), attenuverters, offsets, switches etc
if I wanted 2 disting mk4s I'd buy the EX model instead - more features etc etc
"some of the best base-level info to remember can be found in Jim's sigfile" @Lugia
Utility modules are the dull polish that makes the shiny modules actually shine!!!
sound sources < sound modifiers < modulation sources < utilities