Employers owe a duty under common law and statute to safeguard the health and safety of employees and others. There are also many regulations setting out what must be done in certain situations.
In most instances, a balancing exercise should be undertaken to consider the likelihood and severity of the risk, compared to the cost of protecting against it. However, the impecuniosity of the employer is not a factor: the employer should not undertake the work if it cannot do it safely.
The employer can be liable to damages and criminal fines if it breaches the duty.
An office-holder in control of an employer can be criminally liable (up to two years imprisonment) for a breach of a regulation, and could be personally liable for certain damages for breach of the common law duty (although this is usually insured against).