Lead generation campaign

Hi, I've started working for a start-up (week three) and have very little time to test a B2B product and marketing approach. So far I've contacted people via email (no luck) and have contacted larger membership bodies for my target audience (also no luck). The idea is to have five people test the product each week, but week three and I've only managed to find two people. I'm hoping to have a snowball effect once I get a few people on-board, but was wondering if anyone has any advice on how to find people? The target market is businesses in England. I've been thinking of: telephone outreach, landing pages and social media ads, LinkedIn outreach - in addition to currently unsuccessful email outreach. I can't do press etc because the funding for this hasn't officially been announced. The work culture is quite intense and I feel like I can't do anything right, and have also been unwell - taking time off at the moment. The product has no brand and no assets, and these will be developed after speaking to potential consumers. All help will be invaluable.