Hi Math,
Your best off doing this yourself, as it's not woth £50 a month for something that is quite easy to do.
One of the best ways, if you haven't already to get your site ranked high in the search engines, for your keywords and key phrases is to ensure your site has a good number of incoming links from quality sites.
Also make sure that your site reflects the keywords/key phrases that you are looking for - they should be in your title tag and in your initial paragraphs. Don't however over do it, or it will look like "keyword stuffing" and you will do more damage than good - just make sure they are there in a natural fashion.
Don't aim for the most popular keywords; you will have a much harder time achieving success. Do some analysis using a tool such as Keyword services for professional search engine optimization, and aim for keywords and key phrases for which you have a fighting chance.
Have a HTML linking directory on your site and gather links from related content sites that have a good Page Rank on that specific page your link will appear.
Google usually puts new sites at the bottom of the pile for a few months but there's nothing you can do about it, just keep getting the links.
Add links to all your pages at the bottom of the all pages
Add descriptions for all your images.
To see how a search engine bot views your pages go to
Website Webmaster Search Engine Tools
Remember to gain the best Page Rank (which will entice other webmasters to link to you) add a link to each page on your home page (at the bottom of the page as a simple text link).
It does make you feel good to see your site on the first pages.