and I use that term loosely...
for that 'isn't it way to late idea of quarantine for 14 days'...
Now, the dear French have applied a Quid Pro Quo arrangement meaning that if you trasvel to France (and your occupation is not on the exceptions list) you will be 'invited' to an area where you'll be quarantined for 14 days.
As to the interpretation of the the word 'invited' means.... will be up to police/customs/agents in France.
Here is an extract

Toutefois, pour les voyageurs en provenance de pays européens dont les autorités auraient décidé, de façon non-coordonnée, d’appliquer une mesure de quatorzaine aux voyageurs entrant sur leur territoire depuis des pays européens, une quatorzaine volontaire sera demandée, par réciprocité. Ainsi les voyageurs arrivant, par voie aérienne uniquement, depuis l’Espagne, seront invités, à compter du lundi 25 mai, à effectuer une quarantaine volontaire, car l’Espagne a mis en place le 15 mai un système de quarantaine pour les voyageurs arrivant en Espagne par avion. Cela vaut pour les voyageurs espagnols, français et de toute nationalité. De la même façon, les voyageurs en provenance du Royaume Uni, quelle que soit leur nationalité, seront invités à effectuer une quatorzaine lorsque la mesure britannique de quatorzaine, annoncée ce soir, entrera effectivement en vigueur.

and translated for Mr Scott so that he does not summarily delete the post (again) he cannot understand.Doesn't everyone know about Google Translate? here .: ( even if the site is in English)

For travellers from European countries whose authorities have decided, in a non-coordinated manner, to apply quarantine measure to travellers entering their territory from European countries, a voluntary fortnight will be requested, by reciprocity. Unless you have symptoms in which case it will be mandatory.

Well done Boris ...

Travellers arriving by air only from Spain will therefore be invited, from Monday 25 May, to carry out a voluntary quarantine, since Spain implemented a quarantine system for travellers arriving on 15 May. in Spain by plane. This applies to travellers from Spain, France and any nationality. Similarly, travellers from the United Kingdom, regardless of their nationality, will be invited to complete a fortnight when the British fortnight measure, announced this evening, comes into effect.

Link to official site here
PDF attached

Site where you can download documentation required at the border is here

Not enforceable I suspect.
I know someone who took the Hull Zeebrugger ferry 3 days ago - no problems and is travelling through Europe- the borders are unmanned.
If you’re worried about coming back you can get a ferry from France or Spain to Ireland then on to England.
There’s mass congregations in every city in England at the moment and they are powerless - I doubt they’ll be willing or able to process the hoards coming back from the costas or wherever at the end of August :

Sorry Flipflop- a 'Non' from the French Authorities is highly enforceable!

Latest update direct from a telephone conversation I had this afternoon with the French Immigration office in Coquelles
Unless your profession is one of those listed, the answer is 'NON' you may not drive into France for a holiday.
The vehicle type is irrelevant.
They have no further information but are happy to be called on a weekly basis as things change so fast.
I've read 'tit-bits' about new 'possibilities' from 15th June and 1st July but nothing which can be confirmed by the relevant authorities.
It's a waiting game...

Right now maybe, only maybe.
But I suspect the French government are keen to get the economy going and France is the most visited country in the world so tourism is a massive income for them.
Certainly the British government are powerless at the moment and I can’t see that changing when the hordes start heading for the sun.
We have a 3 week trip planned for the end of August beginning of September and, if I was a betting man, I’d stick a few quid on us going.
If the virus bounces back it will be when the weather turns in October (my opinion only) - holiday season will be over.
Unfortunately if it does bounce back and there’s another lockdown I fear the financial fallout will change the world forever.
Hopefully see you on the road.

It seems your optimism has paid off Flipflop!

As from today Monday 15th June 2020,
British passport holders can now enter France for a holiday provided that they:
1- Have a valid passport
2- Complete the Formulaire de Declaration sur l'honneur in duplicate (one for you and one for Immigration)
3-That each person has sufficient funds for their stay in France and medical insurance which includes repatriation.

On that form, Brits must write the address where they are going to be and their mobile number.
OR and here comes the best bit:
For those who wish to wander as travellers do, whether using a tent or camping car, this is now allowed provided you state on the form ' 'voyage itinérant' and include your mobile number
I was told the reason for this is to help them contact you in case of virus flare-up and to give you updates as to what to do should this occur.

This information was given to me during my telephone conversation with a senior immigration officer in France this morning.

Time to fill up and check those tyre pressures.
Usual Caveat - It is your responsibility to check the accuracy of this post- [ it was at 09:25 today] as things can change in a blink of an eye!

Great news indeed, thanks for posting.
On the subject of a quarantine period upon return to the UK I am equally optimistic - I think Boris will bow down to the airlines and holiday companies and scrap it.
I’m just waiting for Spain to open up as we will be travelling down as far as Cuenca - my optimism knows no bounds