A couple of species I have tried to add but they're not on your approved list of species. Two examples: Iris Sawfly Rhadinoceraea micans, Probably common in the UK and easy to recognise in its larval form. And the parasite Leuchloridium varie on Amber. it would be very interesting to know its UK distribution.
Iris Sawfly Rhadinoceraea micans is available to add - I've recorded it several times and have just checked and it came up fine.
In general terms, iRecord uses the UK Species Inventory species list, maintained by staff at the Natural History Museum, so if you notice species that have definitely been recorded in the UK then they are the people to contact to have them added.
In terms of the Leucochloridium, as there are four species already on the UK list - we have Leucochloridium paradoxum (green-banded) and perturbatum (brown-banded) at Wheatfen in Norfolk. I suspect that it might be the case that brown-banded records in the UK are thought to relate to perturbatum or one of the other species rather than L. varie, or that it is a synonym of one of them.