No idea for choldrith LA, monsters of faerun has stats for them but LA is hard to pin down as name what stats are for PC use. I advice go use a drider as it has LA listed and HD plus some information what stats you gain as PC.<br/><br/>As note I may allow cleric spellcasting for driders instead sorcery, as I think sorcery being weird default for them but could imagine a failed priestess would keep spellcasting ability as cleric but loose the class itself. You could be mystic theurge (combine sorcery from drider with clerical levels) or enter other cleric PrC. Indeed, arachne would be PrC where driders cannot enter. Arachnomancer would be possible with your sorcery spellcasting as drider and that would give you respect among drow being 'mistress of spiders'. Even consider transformation was not shame from Lolth but help you attune to arachnids.<br/><br/>But drider cleric would work just fine, could remain even in church as she has proven Lolth still listens your prayers. But you would be disliked or considered low ranked despite power you wield.