Is quarantining required if you change country?

[Deinonychus]

We are booked to go to Greece this week and I am nervously watching the covid rate increase. If Greece is put on the quarantine list but we leave Greece before the deadline and go to another country (e.g. Italy, Germany) that isn’t on the list, would this mean we don’t need to quarantine when we come home?

Yes

Great, thank you

Yes, but you can count your days in eg Italy as part of your 14 days quarantine

Everybody entering Italy from Greece has to quarantine for 14 days.

Ah ok, will check the entry requirements for Italy. Had only looked at Germany which seemed to say there was no restriction.

Why would I need to be counting the days in Italy for quarantine if I left Greece before the U.K. deadline?

(presuming you mean coming into one of the regions with port connections to Greece and/or a long stopover)
Puglia, Tuscany and a couple of others definitely require 14 day quarantine from Greece.

I meant that the UK government do not allow you to have normal movement in the UK for 14 days after you leave a country on the quarantine list. So eg if you love France today but go via Ireland for 10 days your only need to quarantine (subject to whatever the quarantine rules are in ireland). But once you got to the UK you'd only have to do 4 days.

Leave France, not love France.