Huh, I'd have thought Heinlein would have known better. Writing yourself is a hard trick to pull off, as you can't be too perfect, nor too flawed. One of the few I think could have pullled it off was the late, great Terry Pratchett (I didn't reccomend his books to you already, as I assume you've already read him). He has the sense of humor to make it work.
A slight warning: the first Laundry Files novel is kind of in-jokey. Not that the others aren't (it is about a programmer/magician (there isn't really much difference, in-universe) stuck inside a government bureau whose job is to fight Lovecraftian horrors from another dimension, after all), but the in the first book they can be kind of grating, even for us, the intended audience.
So if the offhand references to Symbolics, Alan Turing formalizing magic, in part by disproving the Church-Turing thesis (but that may have been retconned?), Volume 4 of Knuth, and other geeky in-jokes sound like nails on a chalkboard to you, don't worry, it gets better (by the end of the book, actually. The jokes pretty much disappear once you reach The Archives).