Here is a copy of what the drider template says about spellcasting.......
Spellcasting: A drider casts spells as a cleric, sorcerer, or wizard with a caster level equal to 6 or three less than its racial HD, whichever is higher. It does not gain any other class abilities. If the base creature can already cast spells as a racial ability (not from any class), it can cast spells from one of the above classes in addition to spells it already knows but does not gain any of its class abilities.
I am reading this as my character can cast spells like a 6th level cleric, meaning i get cleric spell slots to be able to use. Am I understanding this correctly ?
Thanks for any replies.
Mike