It sounds like they are asking if you directly employ the staff you use - ie working under your supervision which can mean on your books or self employed help. Employing a sub contractor would be just picking up the phone and getting another firm in to do the work on your behalf. I'm not allowed to sub contract on my county council jobs but that dosn't mean I can't hire a helper.
I would disclose that you would employ the services of specialist contractors when required, as you say may be oven cleaner, carpet cleaner or even pest controller for fleas etc
Be prepared to supply rams and cosh - risk assessments, method statements, care of substances hazardous to health - this is where you'll come unstuck if you buy supermarket products rather than from a cleaning supplier