You know already that your choices are limited.
You know already that a visa application cannot be submitted without a 'clear' result certificate from the UKBA approved clinic.
Do be aware that the all-clear certificate is valid only for 6 months.
There has not been many members who have been unable to secure an 'all clear' despite some explainable abnormalities.
Some folks have needed a sputum test. Those that followed up reported needing a course of anti-biotics for quite some time.
As I recall they were advised to follow a minimum 6 month treatment before being allowed to re-apply for TB certificate.
They need to provide evidence of having been successfully treated in addition to being certified free of TB infection.
Sorry I really can't remember their names. The last case I knew about the wife was clear but the child was not. Very unfortunate.