You will need about £75 per day each, plus your ticket to live as a backpack tourist in Western Europe.
But if you are willing to go farther to the east you will likely be able go get by on £50 per day.
So safe up a bit more, buy cheap flights to somewhere in the east, Prague, Budapest, somewhere like that.
Forget Amsterdam and Paris those are way above your budget, and be careful in Italy. And at more small towns and villages around Zagreb and Split.
For how long, and is the £1k for both of you or each, and does it have to pay the ticket(s) also or just your living costs?
Yes if for one person for one week.
That's not nearly enough.