In reply to compost:
I had to look that up, not being a club runner!
For anyone else who also isn't:
https://kirkstallharriers.org.uk/new/socials/fell-running/
Races are placed into Fell Runners Association (FRA) race categories. The categories have two letters which refer to the steepness of the route and length of the race:
1. Ascent (Steepness)
Category “A” Event
Should average not less than 50 metres climb per kilometre
Should not have more than 20% of the race distance on road
Should be at least 1.5 kilometres in length.
Category “B” Event
Should average not less than 25 metres climb per kilometre.
Should not have more than 30% of the race distance on road
Category “C” Event
Should average not less than 20 metres climb per kilometre.
Should not have more than 40% of the race distance on road
Should contain some genuine fell terrain
2. Race Length
Category “L” (long) race is 20 kilometres or over
Category “M” (medium) race is over 10 kilometres but less than 20 kilometres
Category “S” (short) race is 10 kilometres or less
So, an AS race is short and very steep, a CL is long and relatively less steep. A shortish BM is probably a good one to choose first.