I haven't had an issue with this in the past, my suppliers have done as I asked and provided. I agree with you as you need to be able to access the information as it is on your premises.

lombard, is it your employees or customers who are exposed to the hazardous substances in normal circumstances. If not, I suggest that all that is necessary is for emergency information/procedures to be made available to you. The employer has presumably done his own assessment and implemented an appropriate control regime, which may involve storage in a locked cupboard. Take a view on the packaging information - if its labelled as methyl ethyl death then you have cause for grave concern. If your people are using the stuff or the chance of exposure is significant then do your own assessment and devise your own controls.

Answered above - but you don't state amounts stored and so.... http://www.hse.gov.uk/pubns/books/hsg71.htm may provide an insight into requirements. If it's flour / oil or other flammables and the quantities are high the results of fire or DSEAR assessments may be more relevant.

Your first aider or emergency / medical staff would find the information they need much more easily, reliably and authoritatively from the msds than from the COSHH assessment. And if your staff are at risk of exposure, then you too could do with the msds as you'll need to do your own COSHH assessment. So all in all I think you'd be better off asking for the msds.

A COSHH assessment could indeed be like that - but many are not. In fact a good COSHH assessment is activity-based not substance-based and so doesn't usually take the format of an information sheet about a single chemical, which is what is wanted for emergency use. It will also contain information that is surplus to the emergency requirements, such as the quantities used and the conditions of use, possibly in some detail. At the same time it is unlikely to reproduce the detailed toxicological section of the msds or the "notes for physician" if any. COSHH assessments are not generally designed to convey the emergency information quickly, and even if this information is fully contained within the COSHH assessment, it's all the more difficult to find this information when it's presented in an unfamiliar format. The advantage of an msds for finding information in an emergency is that they have a standard layout, so the responder knows which section to refer to. So even though there is surplus information, the relevant bits are easily found. The other advantage of the msds is that the information about the substance is straight from the supplier, not filtered through someone's more or less reliable interpretation as in a COSHH assessment.

This is YOUR work site so therefore YOUR rules. If you ask for COSHH assessments or MSDS sheets then they should be supplying them. They are being a bit cheeky in my opinion, it's not an unreasonable request. Check with your contracts department. There must be something stating that they must follow your rules while on site.