English only on VDLP ?

The common language of international pilgrims is English on the VdlP, also.
Shopkeepers, locals, etc do not speak English as a rule....but like the CF you learn to get by. It just makes it more interesting. Unless you have an emergency it should not be a problem.

The way is marked pretty well...except in the railroad construction areas. I don't know the status of that now..I last went through in 2013.

There probably will not be large numbers of pilgrims in mid July because of the heat. I found it became a bit more tolerable after Salamanca in mid-August and the number of pilgrims increased as I went North and it cooled down to just "HOT".

There were about 1,500 (only 168 leaving Sevilla) pilgrims last July getting compostelas for walking the VDLP, so there will be about 50 fellow pilgrims per day. I don't think it ever gets cool in July!

Buen camino.

It is going to be VERY HOT and not something I would do ...... but it is YOUR camino.

I wish you well

I did it in April/May and wouldn't dream of doing it in July. Whilst English was widely spoken among fellow pilgrims, it was not commonly spoken by locals.

I'm doing the VDLP starting June 10 and I'm expecting it to be totally uncomfortable. I have the advantage that I live in a tropical area so am used to extreme temps and humidity but I would very much hesitate to start much later. By July 1 I hope to be starting the Sanabres. I'm hoping that Salamanca will be the start of normal hot weather rather than full "frypan of Europe" hot weather. Which is why on the unavoidably long stretches I will be assuming that I need 1 litre water per hour. When I'm walking here in Darwin I'm finding I do best drinking exactly that because I sweat like a pig. I'm expecting greater evaporation in Spain due to less humidity but that means you don't realise how how dry you are getting. Thirst kicks in at 2-3% dehydration. You don't want to get over 5%. So I will have a very loaded pack on those long stretches but at least the weight will go down during the trek.
I'm only expecting to see a handful of people start each day...but do you really need more? I think the potential isolation is one of the challenges of the VDLP.

Donna, I'm Scottish so walking in the heat is fairly alien to me. I walked in July. There were other people, particularly after Zamora. Don't fret about the heat.You'll need very little in your backpack(everything dries so quickly) so transplant it with water.Wear a hat and you'll be grand. It was never actually uncomfortable (bar a day's walk to Aldaneuvea)

I think Donna's concern is in the South between Sevilla and Salamanca.

The challenge in mid August was to find any relief from the sun. I tried to start walking before dawn to get in some time before the sun came up in force.
I had to do some serious scouting the night before to insure I could find my way in the morning. The VdlP has some issues with markings in many areas and finding them in the dark was not something I excel at. Actually, I have problems in the light as I tend to zone out and not really pay attention.
I recall the the temp would usually stay in the 30c (90f) at night and by 9 am with full sun the temperature would be in the 40s and 50s and as high as 55c on the asphalt, according to a small thermometer I had and confirmed by the few bike riders that came by. They would almost always stop and check on me and offer water. They were usually carrying large amounts.
The few bikers were mostly young Italians and riding alone. I was very impressed by the concern.
This was for the first couple of weeks. As I said before, it improved as I went North.

I had a problem of my water getting hot and very difficult to drink.
An umbrella was a great relief and I highly recommend you pick one up in Sevilla before you start. A big canopy is wonderful. You are still hot but not being seared by the full sun.
I suggest you will find the conditions much less severe in June.