If the horn is going off for no reason it could be a shorted siren but some electrical diagnosis is needed here.
Use this link to find a good shop near you.
https://repairpal.com/repair-shops
Alex
RepairPal Certified shops can diagnose and repair your 2011 Land Rover LR2. They provide transparent pricing with a minimum 12-month or 12,000-mile warranty on repairs and services.