Then grab Dark Crusade and Soulstorm, and download the Firestorm over Kronus mod for a TT-ish experience. It isn't exactly TT since it is real-time and compromises between RTS gameplay and TT stats have to be made, but its the closest you can get without playing actual TT, and the quality of it is simply mind-blowing.
Original 596 x 702
Yo dawg, we heard you like serving the Emperor so we put skulls on your skulls you can venerate him while you venerate him.
Oh, and the Ultramarines Omnibus is good, but the Eisenhorn and Ravenor omnibuses are pretty much required reading for a fan of the 40k universe, and the Gaunt's Ghosts novels do an exceptional job of portraying the Imperial Guard as something other than faceless meat for the Imperial grinder. And then there's Brothers of the Snake (also by Dan Abnett) which is about a Chapter of Space Marines called the Iron Snakes who hail from a planet called Ithaka and near the end they engage in pitched battle with a massive Orkish horde 300-style with a phalanx formation and lots of sharp pointy spears.
Some other non-Abnett stuff that's good is the Ciaphas Cain, HERO OF THE IMPERIUM! stuff as well as the Horus Heresy novels. But you really should read the Gaunt's Ghosts stuff first, then Eisenhorn, then Ravenor, then whatever you want, as long as it isn't written by C.S. Multilaser... I mean C.S. Goto, Defiler of Fluff and Desecrator of Background.
Oh, I know who C.S. Goto is. He is the originator of much heresy. Though I will point out that the Ultramarines Omnibus does actually make the Guard more than the faceless meatgrinder of the Imperium (same for the PDF of Tarsis Ultra incidentally).
Oh, on the RelicNews forums there's a 40K demotivational picture thread, and it shows a single Terminator surrounded by mounds of guardsmen. Ciaphas Cain's got nothin' on that guy (since the Termi is a hero of the Imperium).
Probably the only thing I really hate about Abnett's work is that he obviously has no understanding of how REAL LASERS WORK. Laser weaponry DOES NOT SUFFER FROM GRAVITY.
There's a couple of TT mods for Winter Assault (which I've got) but I think that it implemented the TT-based stats too well. Right now I'm planning on getting the first Dawn of War II game, as it's rather snapped up my attention. Personally, the ultimate 40K RTS would have both DoW1's morale system AND DoW2's suppression system. I also like how DoW2 handled setup weapons with the firing arcs (it's really cool but doesn't fit a large-scale RTS (like the original DoW games) very well; but it's perfect for the smaller scale of DoW2).
I do know that the same team that did Firestorm over Kronus/Kaurava is also doing a similar mod for DoW2.
I can vouch for Soulstorm but bear in mind I like RTS' and dislike turn based games. It's over the top savage but I kinda like that, always on the brink of extinction feel. I'm sure this is well represented in the literature. But if you're like me, the game is probably how you became aquainted with the franchise to begin with.
That's also one of the things that's awesome about the DoW games. The over-the-top savagery that, IMO, IS Warhammer 40,000. Now if only there was a mod with Kharn ('cause ya know Kharn's such a great guy).
Sadly GW are very, very protective of their IP's and tend to sling C&D orders on a lot of fan based work (there have been several fan-made 40K movies that will never see the light of day!). Any TT simulators will be firmly in their sights as they would be in direct competition to the actual TT games themselves (and would thus lose GW money).
To make matters worse, the prices for their products are extraordinarily high these days, making it difficult for those ppl who are strapped for cash (such as yourself) to get into the hobby.
As Sareln already mentioned, the best way would be to visit a GW store, or possibly even a hobby store that stocks GW products. Going here should help, as you can also search for gaming groups who you could talk to or join.
The only other way of getting a feel for the TT game is to get hold of a copy of the rulebook (legally or otherwise is up to you) and use placeholder tokens instead of actual minis. Coins become squads and characters (excuse the fact that I'm English, but I think a quarter is close to the size of a standard circular base), cut out pieces of rectangular paper for tanks, etc. Or if you are feeling very artistic, you could use something like MapTool from RPTools.net to virtualise a game (still need to rule book for this though, and moderate digital art skills).
I should point out that the TT game is nothing like DoW (1 or 2). DoW has a very different rule set and was created only to capture the spirit and atmosphere of the 40K setting, so enjoying DoW doesn't automatically mean you will like the TT game.
Incidentally, because GW's products are so expensive, I'm compiling a list of all the models I'm particularly interested. Since I'd probably end up having several squads of a number of them, it helps because now I can figure an approximate total cost.
One thing that WOULD be pretty cool is if GW made a TT simulator and then offered it through Impulse or Steam. They'd probably reach a lot more people than they think.
True, DoW1 and DoW2 are really just inspired by the setting, which is why I suggested Whiskey try out the Firestorm over Kronus mod as it aims to replicate the TT game in an RTS setting. Just take a look at their conversion document. A lot of newbies have a lot of trouble with FoK since they expect it to play just like DoW, and it plays like TT implanted into a RTS setting.
That's probably why I didn't like the TT mods for Winter Assault. Tabletop 40K is a lot more vicious (at least it seems that way); but it can be so much more vicious because it's turnbased. After all, if you just take TT and put it into RTS format, things aren't going to be very fun. This is probably why weapons are a bit different in damage capabilities in the RTS games; to balance out the fact that everything can be going on at the same time.