Insurance like taxes is a mandatory requirement and a such it is a requirement that the breakdown of all charges be shown.. The fact is the Oft made it a requirement that all charges be shown on the first page. Ryanair are failing to do this and so you are unable to obtain a breakdown of what the final cost and charges are until further in the booking process.
They are breaking the law. simple as that...or don't the laws of the Uk that apply to all airlines apply to Ryanair.
The Norwegian Government fined Ryanair some years ago for failing to comply with their legislation. Ryanair soon complied.