Rat Race, you are going to leave a job earning £30,000 + PA , then borrow money from the bank to start a carpet cleaning business , !!!!
Stay in your employment , save the money to buy 2nd hand equipment, start working at the weekends, evenings, and holidays, payback to your self the money it cost to buy your equipment, and then have a really long hard think about "is this want I really want to do " ?
Do not , no matter how "stressed , bored , unhappy etc you are in your present employment give up your job, as all you are going to do is replace it with other problems, and have the extra stress of having no money coming in !!!!!!!!!