I'm interested in why you want to study Psycholgoy at degree level first? Are you planning to go on to teach Psychology GCSE / A-level?
I mean, if you want to be a teacher (Primary / secondary (non psychology) specialisation, then you may be better off completing the teacher training first then picking up Psychology on the OU?
I absolutely advocate studying something you love and will enjoy. But you already know your desire is in teaching and three years and a lot of debt is quite a price to pay for something you won't use professionally. Unless you plan to be a psychology teacher, in which case, crack on!
The stats are pretty easy, don't sweat it. Make accurate notes and you can refer to them whenever you need.