Regarding the numbers they were hard to find but eventually goggle came up with:
England & Wales on Multi-Faith Centre website:
From Scottish Pagan site http://www.scottishpf.org/data.html
I have seen an e-mail to this effect from the ONS about inclusion of Unitarians in "Christian" numbers, however, in my research I never found the total "Christian" number to include any of the "Any other religion" eg Multi-faith centre data. As long as the number of Unitarians can be extracted this is important data.