you are signing in your role as line manager and therefore on behalf of the company, therefore the company remains liable not you individually

Err yes, as has already been said, a bit of a slap is required! Firstly there is no requirement for a manager to sign a PEEP. Of course, a manager may well have some responsibility and/or accountability depending on the circumstances (as opposed to if ANYTHING happens), but this is likely to be an ‘internal’ matter. It is possible, but suggest unlikely that you could be held personally criminally liable, but any failure on your part would have to be pretty significant. In the vast majority of cases the employer would be held to be vicariously liable in the event of a claim for damages/personal injury.

I'm not sure about the good slap - if only? Yes this is scaremongering and they could be disciplined, I'm sure someone could find a reason. If it is a PEEP for an individual you should involve that person in the assessment and they should agree and also sign the document. Don't worry about negligence as long as you are considered competent.

It is important that the purpose of a PEEP is understood and practical by those who are required to implement it. The plan should be simple and capable of being implemented fully to enable the person to evacuate safely. If the plan does not achieve this it is not meeting the requirements needed. The plan should be drawn up with the persons assistance and signed by them to ensure they fully understand the requirements. In this sense the plan is simply a set of instructions to be followed in an emergency. I can not remeber any cases where a person has sued because the plan was either not implemented or was defective in any way. The main point is can the manager be sued if it doesn't work, I suggest the answer is NO as the plan is drawn up with the person involved and the company has the liability not the emploees involved in drawing up the plan anyway.