If you want confirmation, the easiest bits to "check" are Aylesbury and Coventry. London and Birmingham are too big for the features to stand out.
Here is the official HS2 map: https://www.hs2.org.uk/map/?mapView=9_52.0744_-1.8347
To see what it will look like afterwards, try to find High Speed 1, aka the Channel Tunnel Rail Link, now that it's had nearly 20 years to be landscaped and vegetation to grow back. If you don't know what you're looking for, you won't see it.