Were I new to GMing, would the the adventures in the Black Bag Jobs Laundry supplement be good as starting points or should I look elsewhere?
I can say that CASE LAMBENT WITCH looks really good. It doesn't have so much a Lovecraft feel as a spy feel to most of it, but when the Lovecraft begins to arrive it comes on thick, almost too thick since it leads to potentially a very combat-heavy scenario. On the other hand, you do get a couple squads of grunts to keep player character turnover low.
Lost and Found is traditional spycraft and framing, with a twinge of the Lovecraftian. Of all the adventures it feels the least like Lovecraft's works, but it's still very well done. I'd recommend it as the sort of session you run when you're low on players; it's still awesome but it's not as incredibly dangerous as some others.
I've also finished The Shadow over Kafirstan, and it's pretty awesome (in a sense that it sort of touches lesser-seen elements of the Lovecraft mythos, and is, in my opinion, more mind-screwy). It seems better for a starter character, and while it isn't as Dunwichy as some of the others it is really cool in its own ways; it's an approach to Lovecraft that seems almost to have sprung from Coleridge's Kubla Khan.
The Wild Hunt is really good too, bonus points for it working in traditional myth with the Lovecraft Mythos. It's a little contrived and there's a lot of ways for a smaller party to get overpowered, but it's still well done. It's a little thick at times, but it's got the Innsmouth vibe to it.
Secret Agendas is okay, but is more spycraft than Lovecraft-it's really good but the mixture of the two means either that your party will discover the secrets too soon or too late to do anything about it, and failure pretty much mandates shifting to an apocalyptic campaign. I don't recommend it for novice players.
The Signal is a good adventure in a lot of ways, if you like post-apocalyptic Stargate/Lovecraft, so I'd recommend it, but it doesn't reward the characters, which makes sense in context but will probably tick them off to no end. Still, it's exciting, fun, and alien, but it's also somewhat difficult.
Do follow the advice the game gives about the players' standing, if only to keep them from getting murdered. It also looks like the scenarios (at least most of them) would be best played in order, or in a slightly modified order (LAMBENT WITCH has a lot of opportunities to mess up things for everyone, though if it didn't it wouldn't be very fun, now would it?); I'd say The Shadow over Kafirstan may be the best starting point just from my own guess.