Tips for managing a building supplies marketing budget

I'm planning a new hire for a mid-sized building supplies business to manage the marketing budget, the budget is relatively small £150k, I will be taking over the customer/ops arm and need to know what questions and answers should I be expecting during the pitch or interviews I will be arranging shortly? And how should I expect the individual/contractor to manage the budget? my view is this will be managed in line with % of revenue on a monthly basis? but I'm not too sure.
Thanks,