Is there an "overhead bin" on the Eurostar so that you can keep your luggage near you, or is there a luggage area at the end of each car that must be used?
Presume you mean the UK - France service. This site is very helpful and should be able to answer most of your questions about travelling on the Eurostar trains.
http://www.seat61.com/London-Paris-train.htm#On board
Short answers are yes and yes if your luggage will not fit in the overhead space.
Thanks, Linda. (Yes, I meant Paris-to-London service.)