Fieldcraft can take the form of squadron weekend exercises, that would involve campcraft, field cooking, map reading, orienteering and initiative exercises. You'll learn what sort of clothing and equipment to use, and what sort of food you should be eating and why, and important things like calorific value.
It could also be that you attend a week-long 'Green' camp at an RAF or Army camp, and do such activities as assault courses, camouflage & concealment, build shelters, patrol skills, shooting and take part in first aid scenarios. This may all sound a bit daunting at first, but with the training you receive from staff and cadet NCO's, you will quickly become more confident and skilled.
There is also the ultimate development course for Air Cadets - the Junior Leaders Course, a fantastic development course that is spread over an eight month period, aimed at older cadets who hold a serious ambition to join HM Forces.