Not sure this is the answer to your question but, landing on the 27s H10 is deemed separated from ILS traffic, so no issues there.
Departing on the 09s H10 between Gutteridge and Kew is not separated from northbound departures so before a helicopter can go round the corner there must be a suitable gap in northbound departures to allow it to do so. It could be quite a wait for most of the day to find a suitable gap of time to get something like an R22 from Gutteridge to Kew.
I assume it's to do with minimum climb out gradients or summat.