I highly recommend a recumbent bike. I personally would never have considered touring when I rode a "wedgie" bike because it was just so hard on my wrists, back, neck, rear, etc. A recumbent solved all those problems for me and made pedaling all day seem like a reasonable thing to do.
On the other hand, people ride across the US on upright bikes all the time, and you're going a tiny fraction of that distance, so comfort may not be as big an issue. Just my 2 cents (US) worth. Good luck!
Modified Davinci (single speed) and custom Gunnar Rock Tour
Comfort is always an issue, whether it's a short ride or longer ride. 800KM isn't that far but it's a good distance (3-10 days depending on daily mileage).
I haven't looked into bikes that are from the European market (where in Europe are you exactly) but I understand that Thorn and Roberts are both well-known and well-made touring bikes. You may want to look at a hybrid bike (takes the toughness of a MTB and turns it into a touring bike).
As far as "light" goes, well, that depends on how you define "light". To me a bike that's around 20-30lbs is fine. Unless you're racing, there isn't really a huge need for a super light bike. Additionally how are you going to bring your "gear" with you (clothes, personal items, etc.) and where are you staying (camping, B&B, inns, motels, hotels, etc.)? Will you be travelling alone, with a group, with a support vehicle (aka SAG vehicle), etc.?
Where are you.
200euros will not buy you a high quality, lightweight new bike, but you can get something of suitable quality that has been used.
If you were in the UK, then I would suugest looking for a used touring bike. On the European continent these are quite rare, so you may be better off looking for a lightweight, non suspension MTB or treking or hybrid style bike. Recumbent bikes are not much good for riding through rough trails and are much too expensive.
You will need to fix luggage rack, mudguards (fenders) and waterbottles to ther frame by threaded holes. Pannier bags can clip onto the luggage rack. The fully kitted out bike should be easy to lift without your luggage.
For fast mixed riding, a touring grade tyre is good. Schwalbe Marathon and Continental Top Touring are the best.