What sort of cleaning business are you looking to start? General house cleaning?
You can make some really good money doing it.
First tip: don't sell yourself short. You will see people advertising cleaning for £7-£10 an hour. You can get more than that. Molly Maids charges £25 an hour!
(BTW, always talk in terms of "man hours." Two people working together for one hour is two hours of cleaning.)
Working on your own, or with a partner, you can make £12-£15 an hour (before expenses.) If you do a good job, you will be at full capacity pretty quickly.
If you want to hire employees, then you need to plan your business much more carefully and charge a lot more money. You'll need more extensive insurance and legal advice IRT being an employer.
Many (most?) people start out cleaning, themselves, for cash and then grow the business by taking on employees.