There is a pre-mixed blend called Burton Salts to match the Burton on Trent profile for English Ales. I haven't seen any others than that.
It is very possible to build your water from distilled. You'll need a variety of salts (most available at your grocer, definitely available at the LHBS) and a good scale to measure in grams.
Finally, I suggest you obtain a copy of Noonan's "New Brewing Lager Beer" while you may not be interested in Lagers this book has a, IIRC, 45 page chapter devoted entirely to water and how to manipulate it's chemistry.
Good luck and remember ".....tiny, tiiiiiny tap"