So, you’re having a teenager? Congratulations/commiserations. Worried about drugs? We recommend Valium, wine and HRT. Happy you survived the toddler tantrums? Let us introduce you to the eye roll, the cold shoulder and the incoherent mumble.    On the bright side, you’ve reduced your need for Google - your adolescent is now able to frequently correct, hector and lecture you with their strong opinion on everything. And if you feel tired, you’re not imagining it. Teen years are like dog years: for every year your teen ages, you age seven.      You need a survival guide for the testing times ahead. Friends, next-door neighbours and fellow mums of teens Sarah Macdonald and Cathy Wilcox have lived through it all and produced this straight-talking, not entirely sarcastic, informative guide to what for many parents are the most challenging - but interesting and exciting - years in the role.    From A is for Argumentative, Awkward and Angst, to Z is for Zits and Zzzzzs. Because having a toddler is a doddle.