How much is it per unit (e.g. CP1, CP2 etc.)?
Can I take more than two optional modules?
Where are the cheapest prices? (I am willing to travel anywhere, seriously!)
As far as I know, it’s typical exam prices, so £30-40 per paper with an admin fee from the centre on top. You could call some schools/colleges in the area and ask if they accept external candidates, and ask how much they would charge (I would imagine it will be around £200-£300).