find leads for b2b wellbeing business

I'm looking to hire a freelancer to help me find leads for my B2B wellbeing business,. I'm targeting the corporate industry, specifically businesses with medium and large-sized staffs of 100+ employees who have a large number of employees in and around London. So I'm looking for qualified leads—people who are interested in my product or service—rather than just general contact information. If you're experienced in finding qualified leads in this sector, I'd love to hear from you.