Do you mean £700 just for the B12 shots?
I don't know in the UK but if you buy it in Belgium you can buy a loooooot of shots for that price:
http://www.apotheekverschaeve.be/nl/hydroxocobalacet-amp-15-x-3x10mg2ml
That's about €2,80 per shot.
For me the tests were the most expensive part, especially the first round of tests, later he only tests the irregularities and it becomes more affordable.