How can I get help?

I had a "strong positive" result for parietal cell antibodies in September 10 and January 11, have been unwell for several months with some neurological symptoms so I was referred to a neurologist who completely disregarded B12 as an issue for me as my serum level is 258  and in any event she said she could not do any more tests as she would not know how to interpret the results.   My GP is kind and supportive but also says my B12 is within normal limits and we can test it every 12 months as I may go on to develop PA.  Problem is I am ill now but do improve slightly with constant rest and time off work. 

I am at a loss as to what to do.  How can I have more sophisticated tests for B12 deficiency MMA etc? How can I get a referral to anyone who can help or at least investigate further? Are oral or sublingual B12 likely to help me?

I am getting quite desperate and would really appreciate some guidance and can travel and pay if necessary within the UK but feel I need to see the right person. I am worried about going outside the system as I may well develop PA and feel that will be for life and I will need care and do not want to cloud it all and never get the right diagnosis.  As it is I feel I am sitting waiting for my B12 level drop further feeling ill and having many symptoms and getting no real help or guidance.  I am aged 49.

Thanking you in anticipation

Lyndy