You will not need to quarantine on return, but you must take a pre-departure test before you arrive in the UK (a Return PCR or Antigen Fit to Fly test), and a PCR test on return to the UK on Day 2.
Countries that accept Antigen Test for entry from the UK are: Belize, Bulgaria, Cape Verde, Croatia, Czech Republic, Ecuador, France, Germany, Greece, Guatemala, Haiti, Italy, Indonesia, Jamaica, Lithuania, Luxembourg, Montenegro, Norway, Panama, Peru, Portugal, Slovenia, Ukraine, United States.
Day 2 only
Test required on Day 2 after arrival in the UK from a Green list country
Booking reference sent when booked required for PLF on gov.uk
Performed in the clinic for a secure swab and result