Most of the work is coursework based, which you submit online.
There are two short (30 minute) exams over Skype - One for Biology, and one for Chemistry. Both are part of a coursework based unit and are worth about 6 credits each when combined with the coursework for that particular unit.
The awarding body is Ascentis, as opposed to Edexcel. Ascentis is an accredited awarding body and is recognised by most universities. Certainly accepted by every university I have applied to (including those in the Russel Group).