You don't need to get to 34 without the expansion. The highest level activity you can do is 32. Be it if you have the previous expansion (with Crota's End), and completely without any expansion the Nightfall. You can still get there on Nightfalls (and one exotic piece of gear helps if ascended), if your lucky, but otherwise completely unnecessary. Doing Nightfalls currently as a level 32 or a 34 the difference is impossible to tell by human eyes.