Hi Leon
I'm not sure if you're very likely to get many replies that are going to be of help to you.
Income is very different to profit. Many companies here may well have incomes of several hundred thousand pounds (and much more) but may have a surprisingly small profit once they take out all their overheads, particularly staff wages.
On the other hand there will be those contractors who work on their own and turnover, say, £50,000 the vast majority of which is profit.
If your question is really 'How much money could I expect to earn in the cleaning industry' the answer is equally vague - it could be anything from nothing to a substantial amount.
It depend on so many variables: how much money are you are prepared to invest in marketing and equipment, how much time and effort you are prepared to put in to the business, what geographical area do you live in, the state of the economy, how much you know about the industry, your attitude, your ability to get on with other people and, of course, an element of good luck!
At the end of the day you'll get out as much as you put in!
Hope this helps a bit,
Regards
Mike Boxall