Hi Jason, welcome to the "light side" ;)
Honestly, I would not worry too much about what shade of grey you have at the momment... there are SO MANY shades/hues of grey, depending on the war/year, nationality, time at sea, scale effect (huge at 700 scale), etc etc. Not to mention the added variable when you are trying to match Humbrol to Tamiya to MM/testors numbers! Just go with what the instructions say and learn from that.... I know that is what I am doing at the momment, coming back to the hobby after several years absence. Eventually, you will get a feel for the 'correct" grey to be used for specific situations. Most of the time, you will have one "grey" for the horizontal surfaces, a different one for the "vertical" surfaces, something else for the "non-skid" surfaces, and of course, the anti-fouling red (what shade of red?? depends! :), and flat black (maybe!) on some sensor/radar trees. At the 700 scale, construction is a more important variable; joints can be very visible if not glued properly, especially the ones at right angles. I would suggest to use a light mist of primer after construction but prior to main paint job, to detect any flaws or seams.
This is a link to Mike Ashey's set of books, old classics but still give a good intro to ship building (and they are free, PDF format!)
http://mikeashey.com/BOOK-INDEX-PAGE%20.htm
Hope this helps!