Courant juillet prochain seems a little bit formal to be commonly used in everyday language. That would rather be:

en juillet
ce mois de juillet

or

en juillet de cette année (or de l’année prochaine).

Similarly, fin juillet dernier would compete with

à/vers la fin du mois de juillet de l’année dernière

and

à la fin du mois de juillet (dernier).

Disclaimer : In French, relative date references usage can be tricky. The mean depends on both context and author and current date.

“Courant juillet prochain” is quite heavy. I don’t use it and I never hear it in everyday french, only in more formal context (like news and written support). In everyday, you should prefer “courant juillet” or “juillet prochain” ( usage can be both tricky, see below for more explanations)

“Courant juillet” is common used. It refer to the immediate previous or next July. It can be use as fallback value if the mean of “juillet prochain” is equivocal. It can be equivocal in very few case … but is is not the most used. It is less used in June and July.

“juillet prochain” is more common used. In the second part of the year (from July to December) it mean July in immediate next year. In the first part of the year (from January to June) … try to avoid to use it alone. For half of people it mean July from current year, for others mean July from immediate next year… and there are exactly the same trouble with weekdays.
In the first part of the year I almost never use it. Only to target the immediately next July and if July of the next year is a nonsense. (Exemple: “J’ai un contrat d’intérim qui commence en juillet prochain.” and “On fini les travaux dans trois mois, donc juillet prochain sera la dernière ligne droite.“).
If there no nonsense I paraphrase it. To target July from current year I don’t use it but “courant juillet“, “en juillet” or “au mois de juillet“. To target July from the next year, I explicit it and say “en juillet de l’an(née) prochain(e)” or “au mois de juillet de l’an(née) prochain(e)“
In the second part of the year I can use it alone or in explicit version.

“juillet dernier” is also used. It’s little less tricky (more uniform) but differ for months and weekdays:

• from January to July it is July from immediate previous year (obvious no ?)
• from August to December it seem to be July from immediate previous year for huge majority of people
• from August to December it seem to be July from current year for little minority of people
• for weekdays this seem to always be the day from the previous week. And that for almost all people and all target weekdays, independent from current day.

You can take a break after that 😉