"Thrust:
I have thought about using 4 rocket engines that each produce a thrust
of 1200 kg. Ttot Mliftoff (grossweight) therefore i took 1,3 *
3560 kg = ca 4628 kg of thrust.

1200 kg * 4 rocketEngines = 4800 kg
"
I don't know if I'm following what you are saying, but if you want to
go up, without using wings, you need more thrust than gross weight of
vehicle.