For the UK, you’ll certainly need to take a PCR test in the three days before travelling back.
If you’re coming from a Green list country, you’ll need to pay for a Day 2 Covid test after your return.
The same applies to Amber list countries, if you’ve been double vaccinated.
If you’re not fully vaccinated, you’ll also need to pay for a Day 8 Covid test, while staying in isolation at home.
Travellers from Red list countries will need to book a stay in a government-approved quarantine hotel. The cost will include Covid tests.
source: express.co.uk