If you're looking to book holidays, there are plenty of countries open to UK travellers at the moment including France, Spain, Greece, Turkey and the USA.
There are some where you don't need Covid tests if you're vaccinated, and others that don't require Covid tests at all.
For the majority of destinations, you'll need to be able to have a negative PCR test result or proof of vaccination (sometimes even both), and entry rules are ever-evolving.