I have no idea about SEO company in UK. There are many SEO company available online. Among them, i would suggest to you get the SEO service from TuckTail.com here they provide Search engine visibility service which bring traffic to your website. Here they provide you One-click submission of your site in many search engines like Google, Yahoo!, Bing, and AOL etc... and they also provide Powerful reports that show you how to move your website up in search results. It is an International provider.
A run-of-the-mill SEO company won't use the term "doorway page," however, since that's become something of a common dirty word in the industry, they might say stuff like specialized content pages, gateway pages and targeted entry pages. If they use these, be sure that you don't hire them. Look for those who employ ethical, or white-hat methods