In reply to DancingOnRock: Snowdon race is great, but a proper european style mountain race.. not fell race.. crowds, lots of runners, good track, no short cuts really..
Its actually perfect for a novice runner..
Skiddaw? Think its June..
I'd probably look at some of the lakeland trail races too. Bit pricier but get good reviews. Kinder Trog was a good race, 16 miles, not a huge amount of ascent, and marked or marshalled fairly well.. mainly a trail race.. There is some nav but normally people to point the way in the few places you need it..
In Wales, Moel Eilio is an ideal first race, grassy terrain, steep descents.. flagged in a few places, little route choice.