@Georgia147 Just as every new guest deserves a chance to book even though they have no reviews yet, all hosts have to start somewhere. As you yourself aren't new to Airbnb as a guest, I'm sure you know how it all works and haven't found this place on some fake Airbnb site.
One way to set your mind at ease about booking a place is to send the host an Inquiry message before committing yourself to a booking. If the host responds in a timely manner, and is forthcoming and friendly in their responses, and answers any questions you might have in a straightforward way, you'd get an idea if this was a place you could book with confidence. Don't be shy to have a couple back and forths with the host to clarify things and get a "feel" for the host.
I've not yet used Airbnb as a guest, but if I did, I wouldn't ever Instant Book a place myself unless it had a string of glowing reviews- I'd always want to communicate with the host first.