It isn't really super hard anyway, if you know anyone with a membership, they can add you on theirs (and it's cheaper that way anyway). Once you've had that membership for the first year, I think you become eligible yourself.
Do you or your spouse work for any large employers? I believe most local authorities, the NHS, etc are all on the list. Lots of companies are. There are also individual memberships at my local Costco in Cardiff--I'm not sure what the policy is on those, but I think they may be relaxing things a bit.
I had my first one through my mom in the States, but then I got my own because I do have a small business. It was easy enough to set up as I printed some of my invoices and brought one of my home utility bills as the one from my place of business. You can use VAT certificates, but lots of small businesses don't deal with VAT. I was able to set mine up without any VAT stuff. I may have brought a bank statement--can't remember--but I use my personal account as my business is quite small.