None of those faggots actually have friends.
Very ableist of you to assume xir has no headmates.
My wife and I were talking this weekend about learning 40K. Looks like 10th edition is out soon and I was thinking of getting that Leviathan box as a starter.
You guys think that is the right choice?
Firs thing is, get what looks cool, rules go through cycles but if you don't like how your army looks, your motivation to actually build and paint will be nill. Also, pace very well any sort of purchasing since too much plastic will mentally block you from progressing with the tide.
With that out of the way. I believe 40K is a shit game system for the most part. If you just want to play with your wife for shits and giggles it's perfectly serviceable, but the moment you want to start playing with strangers and (god forbid) tournaments, you may find yourself with gigantic asshats on the other side. It is the nature of the beast since this is the most popular miniature game by far, but still, something worth warning you about.
If you try out the game, like the models but think it takes way too long, you can look into One Page Rules Grimdark which is basically a fanmade very simplified ruleset that apes all of the 40k factions and units. I wouldn't file that game as amazing as either, but it plays incredibly quick, which is something I appreciate quite a bit. As a bonus, if by some miracle people play this in your area, they will likely be a lot more chill purely from being a much more fringe community and playing a ruleset that is very much oriented to have a good time. I also have gone through a lot of games, so I can suggest at a minimum models with other sorts of themes or aesthetics (fantasy, western, steampunk, yaddayadda)
Also, don't discount looking into alternative models. There are dime a dozen manufacturers that build alternatives which look fantastic at a lower cost. I'm not going to say "get a printer" but don't discount if you really start getting into the swing of things checking out if anybody prints in your area and accepts orders.
Finally, if you have never painted a miniature in your life, first off, just try whatever without fear, a couple of models that you look back at with nostalgic embarrassment is always a nice little memento to keep and it's also about losing fear. You can always course correct something as long as you aren't dumping layers over layers. Also do consider how much time you really want to invest into it. To do the really amazing shit requires lots of time, but if you just want it to look nice on the table, you can get some very nice looking stuff with minimal investment.