I had this problem about 5 years ago when I wanted a truckload of tracks for various reasons.
However, I'm a very small content creator on YouTube and decided to score a few of my longer things using PRS-licensed music, as they have a discounted bulk rate for Internet-only videos.
So I started registering around and when I got the e-mail requesting information on why I needed access, I just honestly stated that I'm an individual interested in licensing their music, and that was enough. It would've worked even if I hadn't subsequently used their music - they just seemed to want a reasonable assertion that I was at least considering licensing.
That worked for Universal, DeWolfe, RSM, EMI (now KPM music) and Extreme. Cavendish, who were used a lot for Top Gear, didn't ask for any verification at all. I have an account with WCPM, but while I was automatically approved for their non-crippled search, some additional step is necessary for downloading and I never bothered.
