Such was the demand that the union and the company, J D Williams, set up a Union Learning Fund-supported basic skills programme teaching maths and English via IT.
The course is staged at the company's workplace learning centre with help from tutors at Oldham College.
Anne Murphy, of the Union of Shop Distributive and Allied Workers, the project manager, said: "Initially, we had planned to assess 50 people, and then to train 35.
"But we have had 136 people applying for assessment so far and they are still coming forward so we will have well in excess of 35 learners. It's an amazing response.
"The company is being very supportive.
"And through the project we have been able to combine people's personal aims, the compapany's aims andthe union's overall campaign, which is to ensure that our members remain employable."
USDAW had already staged a UFL-supported learning representative course for shop stewards at the company.
Warehouse operative Margaret Garforth, who has already enrolled on both courses, said: "The basic skills course in English is really helping me improve my spelling.
"I managed to get through in the past by always making a joke about it.
"I was ill in childhood at a crucial time and have had spelling problems since."
As well as brushing up on her own basic skills, Margaret described the chance to help others to learn as "a privilege".
"You come across examples of people carrying a newspaper around to hide the fact that they cannot read.
"Now the course can help them come forward and get help.
"Because people know their union reps, they know they will not be betrayed and can talk and get help in confidence."