Communicating with clients, especially when you are in a different country is paramount. Ideally you will want to set up a system that works before you move, whilst you are in the process of moving and once you are there.
My recommendation for this would be to do the following two things:
1. Set up a website and email address.
The site doesn't need to be anything special for now, just clearly state your intentions and list your contact details. You can add blogs, applications and search engine optimisation later. The idea at this point is to just get a domain name registered so you can have a you@yourcompany.com email address.
It's a little known secret but Google will let you register a domain cheaply and as a bonus it will come with gmail and google apps already set up.
Gmail is a great email service and I find Google Apps indespensible for remote working. With Google Apps you can create documents and spreadsheets and invite clients to work on them collaboratively with you.
If you don't like Google for whatever reason try GoDaddy.
2. Set up a Skype account
If you don't already have Skype, you should consider it. The main reason for using it in this scenario is that you can set up some SkypeIn numbers (one as a local France number, one as a local UK number and any more countries you have clients in).
This means that people can call you on a (to them) local number and you can route it to wherever you want. Usually your computer, but you can also set it up to forward calls to your mobile.
You could just give out your mobile number, but once you move this will most likely change and while freelancers are super organised at keeping their address books up to date (ahem!) your clients may not be.
You really don't want someone thinking that you've shut up shop when you're just getting started...
