I'm looking to go inter-railing around Europe in summer 2013 around July/August time for 3 weeks up to a month. I'm planning a route similar to this;
Let me know if you're interested!
Also if anyone would know roughly how much this would cost, it would be very helpful.
im really interested as for costs no idea.
I am thinking of doing the same thing but looking at going in October/November
You will only find out the costs if you do the work.
You are short of this hugely comprehensive guide on all rail travel - http://www.seat61.com/
Don't waste too much time in Zagreb...total waste of time Budapest and Venice are far better