Fundamentally I don't believe fell races (or trail races or road races) are particularly for any type of runner, club runner, non-club runner, fast runner or slow. Edale and the 3P both ask those applying to list their previous AL category race experience and, with Edale, I think they might even do spot checks on that. Equally both apply cut offs too, Edale at Mam Nick and 3P at Ribblehead and Chapel le Dale - those cutoffs really put pressure on runners thinking of biting off more than they can chew.
Either way the only way to get experience in these sort of races is to actually give them a bash
Edit: And another thing, if you then jump from AL fell races to ultra distance stuff, very few runners relatively speaking run as, or at least announce themselves as, club runners - have a look at the
Lakeland 100 entry list for example. For sure you don't see that many club vests at ultra races