Just an update having seen a different GP, he's more amenable than the last one and has agreed to do further tests. So I've just been for these:
Ferritin, Vit D, magnesium, homocysteine and another B12. MMA and any others will probably have to be private. At least he is making an effort suggesting we get these results first and see where we go from there. I'll post the results when I get them. Thanks again for all your support guys.