Great stuff!
Thanks for the replies - It seems that as with most things worth studying, the more you learn in Poker, the more you realise how little you know.
My spreadsheet of records covers only the basics, (date, duration of game, up/down, etc), but it seems clear that really the correct way is to get some decent software to do it for me, so that bb and sb success rates - and I'm sure tons more - can be measured.
Being a newbie (donk?) is seldom pleasant, but judging by this and other threads, this seems the type of forum to quickly bring one up to speed, so thanks again!