Many voucher code web sites use a click-to-reveal format, which requires the web site user to click to reveal the voucher code. The action of clicking places the cookie on the website visitor's computer. In the United Kingdom, the IAB Affiliate Council under chair Matt Bailey announced regulations that stated that "Affiliates must not use a mechanism whereby users are encouraged to click to interact with content where it is unclear or confusing what the outcome will be."
It also shows that you need substantial traffic to make much money through advertising. At a CPM Of £10 with 2 ad units on the site, you would make just £4,000 per month even with a million page views per month for which you serve paid ads to 20% of the audience. Set this to 100% if you are selling all your ad inventory, as for example through Google Adsense.