Just a quick question, when hiking are there opportunities to work as you go? Just small cash-in-hand jobs or is it advised to save for a while before setting off?
A through-hike of the E4 would be a major undertaking, at over 10,000k / 6,500 miles. Unless you're a very powerful walker it's going to take you at least 2 years. A section hike would take many years more.
It's difficult to see how you could realistically undertake this without significant funding. The path passes through many areas where wild camping would be difficult or illegal, so on top of your food you would have to budget for many nights of camp-sites and accommodation.
You really can't rely on picking up casual work on the way. If you're not an EC citizen it wouldn't even be legal. And if you are, the language difficulties are likely to be insurmountable.
What kind of work do you imagine you could find? I can't see how it would be practical. And if you do work your way along the route, how many years are you thinking of investing in the project?
I think you'd be better to draw up a careful budget and have the funds in hand before you set off. It will be much easier to find well-paid work in your own community, so when you hit the trail you can concentrate on your walk without stressing over money.