If starting out I would recommend yellow pages, and leaflet drops.
What you need to consider is your return on your ad price. If you get £862.00 back in a year, and then some of these customer return the following years, you will gradually build your client base up, and the more on board, the more recommendation. You have not lost anything as you had got your £862 back. Do not think that as you are in the yellow pages it will automatically bring in thousands of pounds.
Be realistic you are with lots of other ads and customers will just look at the ads and pick as they feel.
I have a half page ad, I change a higher price than the average, but guarantee the work. We get a lot of clients who want a guarantee good job, and who live in big flash houses. We do not get customers who are ringing round for the cheapest price.
As mentioned what target market do you want.