i agree with others, theres nothing you can really read to prepare for lambing, not sure about calving - havent done it.
Its nothing to worry about, theres nothing complicated to it really, just go with the flow youll pick up all the techniques/info you need within the first few hours. Yeah youll be exhausted by the end, but its deffinately worth it. my lambing experience was my best, i loved gettin stuck in with it, gettin my hands dirty, (so to speak, well literally also, lol!)
i wish i was going lambing this year, cant wait to go next year.