Well, afaik apart from the MLD personel, only the pupils from Haamstede were able to immediately leave to the UK. These were by no means active pilots, but trainees. They were not ready in time to fight in the bob. According to my info, no operational pilot could escape immediately, stuck as they were in Holland (Haamstede is in Zeeland) without aircraft. Some of them got there eventually, but too late to participate. They certainly did not have the chance to withdraw with the allieds like some Belgians could.I recall reading where several did make it to Britain after the Netherlands fell to Germany in May.
In addition to those pilots joining the RAF in time for the BoB, there were Dutch Navy Fokkers and crew that made it over to Britain, which became the core of 320 and 321 Squadron.
Eventually, the RAF formed 322 Squadron, an all Dutch fighter unit, but that was in 1943.