Unfortunately, talking to real people is the only way to guarantee an authentic experience to practice. Just talk to people you know, if you can. You don't even have to tell them you're practicing, just start conversation. I almost exclusively have blocks, and my only way out it to constantly be thinking of the next word I'm gonna say AFTER the block. Because block stutters are psychophysiological, your brain puts too much value on certain words (like names, titles, number, etc), and subconscious pressure to say them accurately causes the block most times. Focusing on the NEXT word helps your subconscious move its attention away from the blocked word. If you're not talking to an actual person who is trying to understand you, of course the block won't manifest because theres no real subconscious value on any of your words. This isn't a flawless strategy (there's no such thing), but it's worth trying! Play with it a bit.