As the search engines swap their directory data between each other, make sure you submit to as many different engines as you can.If you would like some ads on your page with uk content visit our UK Affiliates page.
Unless your site is recieving lots of traffic or search enquiries you stand a good chance of been dropped from a listing for been 'not popular' enough, (some search engines take 2-3 months to list your site so be patient) the only way to beat this, is to submit on a regular basis (once a month to search engines, and to a directory everytime you update your page), particularly to the Big Search Engines , there are some very important directorys that you have to submit to on an individual basis, dmoz, yahoo, altavista , aol.
There are many 'pay' website services, a good one to pay a visit to are Net mechanic who let you try their services for Free.