If you feel like you are working 520 hours a week then the PDA will help you.
If your employer is insured by the NPA (they mostly all are) and you are independently insured by the NPA if the worst happens and you are in a coroners court there will be one NPA solicitor acting to defend your employer and another acting to defend you - Think about it.
Then join the PDA.
Always get indemnity insurance, you may believe you are covered under an employer's insurance but when there is any conflict of interest the employer's insurer will usually be working in the employer's interest. To give an example if an electrical cable on the employer's premises was exposed because the premises had never been rewired for years and you stepped on it you would want to instruct a personal injury solicitor to work in your interests. The employer's insurer would have a conflict of interest as he would be inclined to work for the employer to minimize any damages you might get. The PDA insurance is good.