All Destiny 1 discs, regardless of what it says on the disc, only contain the base game. Any expansions/dlc are included as codes on a piece of paper in the case, so buying a second-hand copy will close to 100% of the time get you the disc with no codes, so unless you just want the base game, or need a replacement disc, there's no point. That note refers to the release date and time for House of Wolves, the second Destiny expansion. Yes, 34 is the highest you can go without getting the expansions. Are on a last-gen, or a current-gen console? You could always buy the expansions through the store on your console, but Amazon might be your cheapest bet. If you're on 360/PS3, a few days ago I saw they had Destiny: The Legendary Edition, which includes up through Taken King (as far as you can go on older console) for less than $20. If you're on XboxOne/PS4 and want every expansion, Amazon had Destiny: The Collection, which includes up through Rise of Iron,the final expansion, for $30. I'm both cases you would be buying the disc and dlc codes, so you'd end up with an extra disc, but that's still probably cheaper than buying just the expansions though your console.
Thank you, that has answered all my questions, I have a ps3, I've checked on the in game purchases and it's seem at it will cost me £15 to get full content (The Taken King, expansion I and expansion II) so I'll probably go for that option. Thanks again PyroAJM