We pay all our guys a percentage of daily turnover, holidays are 24 days a year and are paid at an average of the previous 12 weeks earnings, I don't pay sick pay other than SSP which kicks in after 3 days.
As for paying someone £6 will cost you £10, that's not really true, there are hidden costs like NI (11.8% (70p)) and holiday pay (10% (60p)), but even with everything added on the true cost of an employ will be about 125% - 130% of what you are paying them.
If you pay them £6.00/hr, it will cost you a maximum of about £8.00/hr, however a good worker should be bringing in much more than that for your business.
Once fully trained my window cleaners earn anything between £16K - £24K PA. If they get stopped for the weather they don't get paid, if they take a day off, they don't get paid, however if they go out and do £600 of commercial work in a day then they get paid accordingly. It's swings and roundabouts and all my guys and me prefer it this way.
When training they are on a basic salary of £6.00/hr until they can show they are of a speed where they can earn more on percentage, without getting any complaints from customers. I give them a maximum time of 8 weeks to reach this level, otherwise they're gone.