how much money will i need in euro to travel for eight months around nepal, india australia new zealand?

It's a while since I travelled to these places so can't answer for definite but Nepal and India were/are cheap whilst Oz & NZ are not so (although they're cheaper than the UK for most things). You best guideline is the Lonely Planet website or their guidebooks (go in to any bookshop and browse)...the costs section will give you an idea for meals, accommodation etc that should allow you to come up with a rough budget.

depends on what you plan to buy,,,and your rooms and meals,,