Quitting without notice

My son works for a company who pay weekly, although the pay is very regularly up to 3 weeks late and he only gets paid when he kicks off about it. They just laid off a lot of staff with no notice on the promise they would be paid when the company gets some contract money in. (Not sure how likely this is or when it will happen) Understandably my son has had quite enough of this and wants to leave. He is currently one week behind on pay, and the company hasn’t paid into his pension since November. His contact states he should give 2 weeks notice but he thinks he will never get paid if he does this. He wrote a letter saying he wanted to leave immediately and would like his pay up to date and also his pension contributions. But the company are refusing saying he needs to work his notice period.

He could be prosecuted for breach of contract by just quitting but given the employer has already broken the contract on many occasions where does he stand. Thanks