Hi, (btw, we use our real names here. please read Forum Rules)
Since you already have the 456, you can certainly chance using it for casual recording.
If it hasn't already, this tape will eventually have an issue called Sticky Shed Syndrome (or Soft Binder as it's referred to now).
There's a post about SSS in the "Beginner's Guide" located in a sticky (no pun intended) above the General Forum as well as numerous posts which can be found using "Search".
Tape certainly isn't cheap today but if you plan to do some serious recording and you'd like those tapes to be playable in the future, it's worth buying RMGI or ATR Magnetics tape (these are the two manufacturers who are still producing reel to reel tape).
There are a number of distributors for both of these tapes around the world but a good "one stop shop" for this and other reel to reel supplies, check out;
http://usrecordingmedia.com/It's also in tape users better interest to support these two tape manufacturers to be sure that the supply of tape doesn't stop.(IMHO of course)