Create a website like contentwriters.com

I am looking to build a website more or less exactly the same as contentwriters.com. You can see how it works here: https://contentwriters.com/how-it-works

Currently I manage a team of writers and have multiple clients that all need to be streamlined into one manageable system. I'd be needing a client login where they can order and pay for content directly, and then somewhere for my writers to be able to login also and to be allocated the client's order manually.

I have a decent budget for this project, not exactly sure what is needed so have put £1k as a starting point. I would prefer to work with a UK contractor or team on this to ensure there is no miscommunication. It needs to be a simple construction which will ensure minimal errors moving forward.

Any ideas or suggestions on how to proceed would be welcomed. I'm keen to get this going ASAP, and would ideally like it fully completed and tested by Feb 1st 2019, ready to add new clients and writers to the system.