I haven't had a chance to read through all the replies on this thread, and I have a crazy baby that is bound to cry since I put her down to type this! HAHA But, I have done some looking up on the Costco UK website and it says you have to be a business! This makes my heart cry! ): Is there any way my husband and I can become members? He and I were going to take a Journey to the Reading one or the Watford one this week but I don't want to if there isn't a possible way to get membership.
If there is a way, what items will we need to bring along to start one up?
Many thanks, to all the yanks 
Nope. I worked for Aviva as a customer service rep and qualified as Aviva is part of the financial services community. My partner works for a subsidiary of BT, so he qualified. My sister worked for Cadbury when she lived here, and they qualified as well. All non-union jobs. No self employment involved. Granted these are large companies, but all private sector. NHS, Police, etc should qualify. If youre not sure, you can always call the service desk and they will confirm over the phone.
I got my membership when we were in the States in 2007 and it transferred over, no questions asked. We went back in 2009 and I was able to use my card at the register, no questions asked. Cashier just keyed in the correct code and went right ahead.
Costco here works a lot like how Costco/Price Club of 15 years ago worked.