I think if you can do £100 a day as a new start up, you're doing very well. Don't underprice just to get jobs, try and price a semi at £10 minimum; add more for conservatories and access problems.
If you underprice jobs because you think you've got more chance of getting more customers this way, you're wrong, and you'll suffer for years because of it.
Tell us what you've done so far? Or is this just an initial post?