Well they are certainly wet leases, that much is clear from the CAA link I posted earlier.
It's unlikely that the crews will be familiar with Heathrow unless any of them have moved across from the widebody Airbuses and Boeings that QTR normally operate into LHR.
That said, flying into and out of LHR is largely a case of having implicit trust in ATC. If you can't follow vectors accurately or control your speed precisely then you really shouldn't be flying at all.