While huge question marks linger over summer holidays abroad, one thing is clear: there will be Covid tests. Although some countries, such as Greece, have already suggested that fully vaccinated travellers will not have to provide proof of a negative test, many others may still demand evidence that holidaymakers are Covid-free. And with those under 18 unlikely to be jabbed for some time to come, families could be facing huge added costs to their holidays. On return to the UK, travellers will certainly have to take a test. The Government has confirmed that a ‘traffic light system’ will come into force when international travel restarts. Countries will be categorised as "red", "amber" or "green" depending on the proportion of its population that has been vaccinated, its infection rates and the prevalence of variants of concern. Even travellers from “green” countries will have to pay for and take at least two tests: one shortly before departure to the UK and one on arrival. Most countries require arrivals to show "gold standard" PCR test results, which are lab-analysed and generally provide results within 48 hours. However, an increasing number of destinations, such as Italy, also accept rapid tests which offer results in minutes and are usually cheaper. Here, we break down how the respective tests work and what to look out for when booking one this summer. How do I get a PCR test for travel? With free NHS tests still reserved for those with symptoms, travellers must book private tests. There are two options: ordering a home test kit or booking an appointment at a clinic/drive-through test centre. Most home kits will arrive within 24 hours and should be sent back the same day. They will then be analysed in a lab and you should receive your results within 48 hours – various companies have different guarantees. If your test is negative, you should then be sent a certificate declaring you Covid-free. However, concerns have been raised that, as there is no standardised certificate, they could be forged. Furthermore, it is not always clear how much information is required in each country. As the free NHS test results are just a text message and short email, there is no guarantee that border officials would deem this acceptable. Some companies, such as LloydsPharmacy, whose home kits cost £119, ease fears with example certificates online, which include the name, address and telephone number of both the laboratory and company, plus the name and date of birth of the recipient. Crucially, the date the sample was taken and processed is also recorded. When ordering a kit, it is certainly worth clarifying what will be detailed on your certificate. Tests at clinics tend to have a quicker turnaround. Harley Street Health Centre in London, which offers tests for £175, guarantees results by 8pm the next day. More broadly, DocTap has a network of clinics across London and offers a range of coronavirus tests, including a next day option, for £125. Beyond the capital, Boots has launched a PCR testing service in 100 stores across the country. It promises results within 48 hours and is priced at £99. The advice to customers is to book appointments for between 60-72 hours before their flights. Another option is Vivo Clinics, which has PCR testing centres in 10 UK cities (Belfast, Birmingham, Cardiff, Edinburgh, Glasgow, Leeds, Liverpool, London, Manchester and Newcastle) and charges £149 for its standard service, or £289 for same-day results. The highly rated Corona Test Centre has five clinics in London, plus outposts in Manchester and Birmingham. It provides a reassuring 'fit-to-fly' certificate, which is signed by a doctor (from £145). Gatwick has a drive-though test centre where PCR tests cost only £60 for passengers, though with results generally provided the next day this would mean two trips to the airport.