the two rules that apply are
ADR 12 Glare reduction in field of view.
ADR 69 Full frontal Impact occupant Protection
DOTARS told me that for the 32's ADR69 does not apply but not 100% on the 33's, they did not mention them.
The other usual rules apply with hinging and latching and scoops.
So that means that on a 32, a fibreglass bonnet, carbon fibre or aluminium bonnet is completely legal as long as there is no excessive glare and hinges and is latched correctly.
I do not see why this would be different for an R33. I would seriously contest any fines that have been issued as this has come from Department of Transport themselves.