Dear physiofi,
Very good advice so far, and I'm delighted to see you are seriously considering the downside, as I find when people want to go into business there is often no way to talk them out of it, even with the facts!
If you can move, I highly suggest you try Canada or US, as you could get 2-5 years experience here and save enough to open your own clinic when you got back. If coming over is not feasible, I would say I concur with those who warn against buying ads or sponsorships.
If you can't afford the website, try a facebook site, that will come up on google when people search you. Then people can post feedback and encourage you, and their friends can read it.
The idea of a part time job for a while is very good, but I think if good part time jobs were easy to find in Wales, you'd have gotten two of them together and not be in this dilemma, eh?
The person who said the standards of expectation were higher in private practice, wow, they said a mouthful!!!! That is so true. Your learning curve will be steep. Good Luck whatever you decide.