Not too sure what you all mean by the amount of competitors you have in each area.
I have 8 pages of CC in my Yell Pages but still do well, Stevenage/Welwyn/Hatfield/Hitchin/Letchworth/Luton is a huge area so you are going to have many competitors, but that is offset by the 1000's of houses/offices/Pubs etc.
You might have only 2 competitiors in a small town in Scotland but with only a few houses it would be equally as hard to achive a large customer base.
Dont rely on YP being your saviour, like any business it takes time, do a good job and work will come from that, in 3 years time your biggest earner will be from Recommendations & Regulars not YP.
Phil