Market size model for employee benefits

We're a consulting firm doing market research for an employee benefits company. Our client wants us to do market testing of a new set of employee benefit products that they plan to launch on the market. We're doing a large market survey with HR managers in companies; one deliverable is to quantify the size of potential demand (i.e. the market size) for their benefit products. We need a consultant to plan and execute this market size model. These are conceptual products so there is no existing research to help with this. The consultant will work with us to design the market sizing model, which will need to use published statistics plus survey data on employers' likelihood of using the benefits. The consultant will be responsible for finding the published statistics needed through secondary research and for executing the model, incorporating our survey data inputs.