Sunny
In summary of all the above posts, you are not the responsible person as defined by the Regulatory Reform (Fire Safety) Order 2005. The "responsible person" is a legal term- it is the employer and may include the education authority, the governors and the headmaster - some as a corporate body, others individually accountable so far as they have control. For example in a recent prosecution following a release of asbestos in a Derby school, both the Education Authority and the Headteacher were prosecuted and were found guilty of an offence.
You have been asked to do something for which you obviously feel unprepared and perhaps not competent to do properly. Your must make these concerns clear to your employer but then having done this must follow his instructions. By making your concerns clear - and recording this - it will not be you who is in breach of the Order. The responsible person, if seeking assistance, must ensure that the person giving assistance is competent to do so.
The fact that they have given you documents issued by the arson prevention bureau to work from, rather than the proper DCLG guidance probably indicates that they too are not competent or aware of their duties.
But I finish with the following observation- if the building is small and is of a simple design that complies with the current desgn codes for schools and the building regulations, and has been well maintained and its systems kept up to date then there is no reason why an intelligent person with a grasp of general Health and Safety law and risk assessment techniques should not be able to make a suitable and sufficient assessment of fire risk, This was the Government's stated objective in producing the guidance I referred you to earlier.
I do hope all this helps!