As far as I am aware, the only complete modern English translation of Pliny the Elder is the ten volume H. Rackham translation published in the Loeb Classical Library series. As is usual with the Loeb editions, it doesn't have a lot of extranous notes except for pure philological ones, so you would need a companion monograph for that.

Depending on how much knowledge you have on the subject, if you are a beginner perhaps start off with The Shadow of Vesuvius: A Life of Pliny by Daisy Dunn (Liveright, 2019), or if you already are well versed about the basics but are looking for more indepth studies of particular aspects about the Natural History then it could be either Roman Nature: The Thought of Pliny the Elder by Mary Beagon (Clarendon Press, 1992) or perhaps Pliny the Elder on Science and Technology by John F. Healy (Clarendon Press, 2000).

The historiography of Pliny the Younger and the literature on the subject is a lot more extensive, and his works can be found in a variety of different versions, so I think you will need someone more specialised in the field than me for a comprehensive answer.