The best prices found on momondo for flights to Guam are:
£84 per person with T'way Air
£109 per person with Jin Air
£124 per person with Cebu Pacific
Guam has restricted the entry of all travellers who have been in a country with confirmed COVID-19 cases for more than a week, and do not hold a document certified by DPHSS (Guam Department of Social Health and Services) that confirms they are not infected with COVID-19. The date of the test must not be more than 72 hours before the date of arrival. Travellers who enter Guam without proper documentation will be quarantined. Guam residents may still enter the country. If you are planning to travel to Guam at this time, it is recommended that you stay up to date on current restrictions and follow proper safety measures while in public.