In reply to Lh88:
Adršpach, Teplice, Ostrov and Labské údolí (Elbe valley) are all great for sandstone. As you know, no metal pro is allowed on sandstone, but you can use slings and knots, and there are bolts (more in Ostrov than Adr, be prepared for terrifying runouts). Chalk is heavily frowned upon at Adr, but it seems to be accepted on some of the harder routes. I suggest you join the Facebook group "Lezení - kdy a kde" (Climbing - when and where), where you might find someone who will give you specific advice and maybe meet up.
In and around Prague there is a bit of afternoon trad at Divoká Šárka and Holy Vrch, Unetice, although probably too tame for you, looking at your grade; the rock is a form of schist, and takes metal gear. An hour or so south there's granite at Rovište and limestone at Srbsko, both by the river. If you're into bouldering, try the granite at Petrohrad, an hour or two west of Prague. If you stop in Prague for any length of time and fancy indoors, try Boulder Bar (bouldering only), SmíchOff (climbing and bouldering) and Big Wall (climbing and a bit of bouldering).
Guide books - as far as I know, there's no general guidebook. Labské údolí has two, for right bank and left bank. I don't recall seeing anything in English. Hanibal or Hudy Sport in Prague are probably the best places to buy.
Ropes - My friends tend to use 80m single, but I am sure you wouldn't be short of routes using a 60. I don't know of anyone using doubles here, but I don't have much experience of the sandstone at all.
Post edited at 16:06