I think £100 now would pay just for the running costs bearing in mind that you won't get jobs everyday, look around on the threads and posts to find an average job price or suite price and price per sq ft.
I'd still recommend that you get some training because in 11 years my business has changed loads and so have the carpets and upholstery you can even get suites that when cleaned go from green to pink

you have to know how to reverse it and also the Belgium Wiltons that are now plain in colour and also paper carpets

Machinery has doubled and quadrupled in power and chemicals are much better and some old chemicals just can't be used in the home anymore unless you want a claim from our lovely compensation culture.
Competition is rife but good service beats that hands down providing that you can talk the talk and be and sound knowlegable (see 2nd parragraph)
Don't think that you can carry on where you left off as customers don't just have lesser quality carpets now but also want them as dry as possible with stains gone, they don't just take "oh I tried my best" they want to see action!
If you get into the price game you will lose try rising above it (I've been there and done that) and I would set yourself a target per day of £250, you may not get it everyday and keep advertising because if you want a consistant wage you have to build up your customers and as soon as you stop advertising you won't get any calls for weeks it's call Murphys Law.
Keeping looking in on the boards
Shaun