As the person who established that rituximab is useful in autoimmune disease I would actually advise against this. Rituximab is very unlike most drugs in that you have to understand how to use it in considerable detail in order to give it safely and effectively. Protocols exist but in RA use of protocols has led to a lot more adverse effects than necessary because many rheumatologists do not understand how the drug works. If you find a private clinic in Europe prepared to give it you should think long and hard about whether they actually know what they are doing. My suspicion is that any clinic prepared to give rituxmab privately in ME is very likely not to know what they are doing.
The fact that nobody is using it in the UK yet, even in a trial, is largely a reflection of the fact that physicians are not confident that they know enough about what they would be doing to justify subjecting patients to the potential risks.