Don't really want to start messing with the pH being a beginner ...
You're right about not messing with the pH, it can be just a tad tricky!
I also have very hard water, I even managed to check the kH and gH the other day and they were something silly like 14 degrees and 20+ degrees
Liquid Rock!
I spoke to my LFS about this and they seemed to be very anti RO, basically they said that unless you have extremely sensitive fish you shouldn't need to worry about it and that most fish can acclimatise to different pH levels. Now I tend to believe the shop as they don't have or use RO for either their Marine or Tropical tanks, their tank pH was slightly lower than mine (mine is 8 and there's is around 7.6) but I put this down to the heavy stocking and maturity of the tanks.
I would find out what the pH is at your LFS and ask them what water they use in their tanks, you may find that they keep all sorts in exactly the same water as you have.
I was thinking maybe of starting with Platy and Guppy which seem to like more alkaline conditions reading the Fish Index.
Also, I would avoid guppies, they have been the bane of my life over the past few weeks, the little plecs I have are fine, settled in well and no signs of illness, the guppies have just been dying off one by one and now I'm down to 3.
The ones that survived are the ones that are 'different' from the others in the tank at the LFS, one had shorter fins than the rest, one was mixed colours when his brothers were all yellow. Basically if you do get them look for ones that might have a mixed gene pool and have been there a long time (a few weeks).