Not sure I understand the options in the poll to be honest! What's looking wooker?!!
Do you run portable equipment or a truckmount?
If you're using a portable, have you thought about how the economics would work out by upgrading to a truckmount so you can get more work done in less time on your own?
Taking on an employee, you're entering the premium-rate torture chamber of British bureaucracy. Employees have all sorts of stupid rights, like you have to buy them £££'s worth of protective clothing and equipment which they will break and/or lose, meaning that BY LAW you have to go and buy it all over again.
Employees generally don't care as much as you will if they break your machines, tools, equipment or vehicles, so they're more likely to abuse them. They don't properly understand the implications involved if they destroy a customer's carpets/suite etc. Yes you're insured but with a whacking great excess to pay on a claim.
Employees have this bizarre thing where they expect the right not to come into work for several weeks of the year and still get paid for it. I think I've heard some people refer to this sort of activity as "Having A Holiday". Must look that up in the dictionary one day.
The overheads of employing can spiral way above initial predictions, which is really what I'm trying to say

Don't just think of it as a percentage of your turnover, or a set weekly outgoing