If the wing has a Chord of 150 mm and a span of 800 mm, what about the distance to the tail? anf the size of horizontal and vertical stabilizer?
Well, you size your vertical and horizontal stabilizers based on their distance from the center of gravity.
torque around the the center of gravity is force × distance
So the first question is how long the fuselage will be. Remember that the tail torque must always be able to be stronger than torque produced by the wing and/or fuselage under all possible flight conditions including stalls.
Other considerations are:
1. pitching moments at various angles of attack
2. distance of wing center of pressure from center of gravity
3. how aerobatic will your plane be (how many G forces can it withstand) - size of rudder and elevator/stabilator control surfaces
4. thrust line and magnitude
Size and throw of elevator and rudder will also be critical. It is recommended to use an existing design as a starting point. Plenty of 800 mm gliders can be found at the hobby store.