Slovenia is great - give it a go!
One of the best resources pre-trip are Cicerone Guides - there is at least one for Slovenia:
https://www.cicerone.co.uk/product/detail.cfm/book/709/title/the-julian-alps-of-slovenia#.WTURf-vyvIUThere is good walking to be had in a number of places, but the usual key bases are Bled, Bohinj and Kranjska Gora, all of which have good routes in/near to them.
Maps are available, but we found buying them in-resort much easier. Be aware that although there are lots of good routes, it's not like the UK with paths going everywhere - more like the alpine model with distinct routes to specific places (lakes, summits, villages, etc). You may need to use a bit of local transport/taxis to get the best out of the area.
I've hiked from Kranjska Gora and Bohinj, and also in the Karavanke Mountains from Jezersko - drop me a PM if you'd like a bit more info on any of the areas mentioned, and I'll do what I can.
Cheers
Glovepuppet