do i need a passport to go from greece to england?

Answer 1

According to European Union laws No.
Also Greece and UK are Shenghen area so there are no border checks and you theoretically do not need to have a passport. You can use your ID instead of passport. But you mast have a new Greek ID with Latin characters! If you use an older Greek ID which is only in Greek you might have a problem!
There is also a chance that a country might request the use of passport like UK did when the terrorist attacks took place in London!
So just to be sure use a Passport especially the new ones with bio-metrical information!

Answer 2

Yes, you do. UK and Ireland are not part of "Shenghen visa area" (containing all other "old" EU members), so you have to show a passport on the borders. Unless you are a European (member of an EU state) - then you can just show your domestic ID card.

Within the Shenghen area (e.g., between Germany and France), there are no border checks so you theoretically do not need to have a passport. However, in most countries, police can ask you any time to identify yourself and you will surely need it before boarding any aircraft or checking in a hotel. So, have your passport or EU identity card with you at a safe place all the time.
http://en.wikipedia.org/wiki/Schengen_Agreement

Answer 3

Yes, from the country of which you are a citizen.

Answer 4

YES