Iron Lights by Felicity Banks

Emmeline Muchamore was respectable once. Her sweetheart, Matilda Newry, certainly put a stop to that. But when Emmeline gains magical insight into a disastrous future battle, she weaponises her wild reputation in order to draw trouble and death away from her adopted home … risking everything and everyone she loves in the process. Iron Lights is a steam-powered tale of honour, love, magic, adventure, and mechanical spiders.