Build a Website

I am looking for a freelance web and app builder to help me with my new business idea. My idea is web based to start off with but eventually will hopefully also be app based too. The website and app will be searched based (visitors will be able to search for services in their area, make an account etc.) so from what I can imagine, HTML, CSS, PHP is required at the very minimum. This is a slow project so the freelancer will need to be happy to receive a certain amount of money in a month, do whatever that amount covers, then receive another amount of money the next month, do whatever that amount covers, so on and so on until the work is completed. If you can design graphics also then that would be great. From my understanding, the website is not a very difficult design for a good designer. I have no files to attach nor a budget in mind, this will be discussed with whoever wants the job. I am based in the UK so freelancer must have good English, good references/reviews, examples of work and be good at keeping communication. They must also be willing to sign a contract of ownership of the work.