Well, the time has come that my players have to aboard a space hulk. My concern is about the ambient, descriptions and feeling in general. What do you think?

That really depends on the type of space hulk.

Is it an unclaimed composite of ships and rocks driven together by the turbulent forces of the sea of souls?

If so then it should be without rhyme or reason, corridors that go no-where and twisted/compacted rooms inter-meshed with grotesquely stretched areas and gaping voids. Try and invoke the atmosphere of a shipwreck. Ancient and forgotten with all sense of purpose lost.

It may have ancient treasure or technology but there is no reason that there should be a way to get to it without cutting through metres and metres of solid rock.

If it has been claimed (by greenskins, genestealers, chaos etc...) then the feel would be determined by who claimed it but at least there should be some sort of map that makes sense (from some perspective) as the beings that claimed it are going to want to get from room to room and are probably going to want to keep their stuff somewhere.

You might want to check out the Deathwatch adventure Ark of Lost Souls . It has a fair amount 'set dressing' for a space hulk-set adventure, including some charts for generating random areas of a 'hulk.

Also [ shameless self-promotion alert! ] I came up with a variety of 'vermin'- minor non-mission-related monsters- to use in my campaign; a link to these is in my signature.

Finally, a bit of practical advice: I recommend mapping out the areas your players will be exploring. When I ran my long-ish space hulk adventure, I started out relying purely on verbal descriptions and general directions and distances, but this proved to be quite unsatisfying in actual play. So, half-way through the adventure I switched to D&D -style graph paper maps and treated it as a straight-forward 'dungeon crawl'.

Thank you both for the help, it has made my task more easy.

There is a DH 1 adventure set in a space hulk as well (one of the "Purge the Unclean" anthology adventures). It has some interesting moments imo.

Generally try and make it as oppresive and intimidating as possible, have them make random perception checks and regardless if they pass or fall tell them they could have sworn they saw something move... if they passed make it so when they go to investigate (if they do) either some kinda alien or human trys to grab them begging for help or make the entire section collapse! that should keep them worried also after there a little ways in destroy any easy way back to their ship... if its a shuttle destroy the corridors they came down so they have to hunt for a new way back if by teleportarium have the shields come back online or the comms go dead suddenly, hell you could have the astropath suddenly hear the wailing of the damned and it blocks any incoming or outgoing telepathy