Hosting solutions and costs can vary widely depending on your requirements. However, as a guide you might like to consider what sort of site you require. For example, a static HTML site requires very little space and no database and could be hosted on a server from as little as £50 per annum. While a site that uses a database such as a job board or property site would cost more as it requires more resources.
Consider how your site might grow over the coming 3-5 years and the sorts of services you would like to offer as this will give a clearer picture of the resources required and the costs involved.