In reply to Lmc:
SPA, or even CWA is an instructing award, and essentially, how can you instruct well if you dont have any experience?!
To be honest I don't think the standards at CWA level are high enough, or at least thorough enough in assessment. SPA is more thorough from an outdoor experience point of view, but less so on a group management side. Which as an instructor is important.
Anyhow, before I digress, I've witnessed some pretty shocking instructing from those holding NGB awards, as well as those having been trained on the scheme prior to assessment. For the good of your potential clients, please don't rush into these awards.
Why not just start with climbing, and see if you enjoy it?
Find a local wall, and take their beginners course, often grouped with other adults, so you don't need a friend to join at the same time. Then from there you can find partners to climb with. Get clued up and experienced, and if you like it, look to get outside, where you can gain experience there.
For now, forget about SPA, and get into climbing, it's pretty good