Whats your average price per house at the moment?
How many customers do you need to get to £1000 a month?
At say £10 house average you need another 68 customers @ monthly cleans.
You need less than a 1% return on those 10000 leaflets, but is is getting harder out there and seems like quite a few made redundant are giving window cleaning a go, more so now the suns been out for a week

Quite possible you can do it but not gonna be easy (you'll be bored to death come the 3rd week leafleting).
Good luck though