Hi Joanne,
Your employer cannot go into liquidation as he/she is a sole trader!
In case of liquidation the DETE will cover your arrears of wage, holiday pay, minimum notice and statutory redundancy. However, the DETE cap holidays at 20 days per annum and also your weekly wage is capped at €600.
Also, the DETE are swamped at the moment and what used to be a 4 week wait is not closer to 12 weeks!
Being a sole trader your boss is personally responsible to pay you however if he/she fails to do so you can bring your case to the employment appeals tribunal and then if you get a positive decision you can make a claim to the dete but this will take months.
Hope this is of assistance.
Regards
Stephen