I'm writing a story set in the UK 6 years prior to the legalization of civil unions for same sex couples in 2005. I was inspired by a news story about a lesbian couple who, prior to civil unions existing in the US, secured legal union for themselves through adoption. I was going to have the male couple in my story do the same thing. One problem though, I'm not sure what the adoption laws are like in the UK: is it allowed for one adult to adopt another? Is it allowed for a younger adult to adopt a person who's several years older?
ETA: Questions answered in comments thanks to fides.