'Thank you' Boris...

[Toyark]

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