My first event called a fell race was Box Hill in Surrey (!) basically a 7m hilly cross country and virtually zero chance of getting lost but a fair test in its way. First proper fell race was Ras Y Aran in Wales, an up-and-back so again nav very easy. I have lots of walking experience in the hills and quickly pushed myself into events with navigation challenges and no single path, so classic fell stuff. I remember the 'ER' issue but you just have to start lower down the difficulty ladder and (except races requiring evidence of specific experience) you progress as you feel able