The next project (that may take a couple of years to complete) will be one on Hoverflies. You can see an Excel ‘map’ of the number of species currently on the National Recording Scheme database as of 2022 here.
Many tetrads have very few records and there are some Hoverflies that are common and relatively easy to identify, so why not have a go. Especially as the new 3rd edition of Ball and Morris’ identification guide is due in June.