That is a very disappointing response to receive from Samaritans, my understanding is that part of their mandate is to connect people with local services when contacted. NHS Choices has a search function that will provide listings of services in your area and you can find it here http://www.nhs.uk/ServiceDirectories/Pages/ServiceSearchAdditional.aspx?ServiceType=Mentalhealth .
With regards to the GP, they should arrange a review by a Psychiatrist if you request one...it's your right to request a second opinion and the GP should have no issues with arranging this for you.
With regards to your husband believing that he has been permanently changed; try to keep in mind that he is speaking from a state of illness in which his cognition, perspective & interpretations have been altered. He will be able to discuss this matter with you but he will still be responding from a state of illness. He will likely interpret things in a different manner when his mood is lifted but until then you really do need to try and accept that 'it may be the Depression talking'. I often have conversations with my Depressed patients that are similar to the one you are trying to have with your husband and I rarely am able to convince them that their cognition may have shifted whilst they are still depressed. I make it clear to them that it is my opinion that there may be cognitive changes and that we should wait to see how they view things after the Depression has lifted.
Depressed individuals can develop difficulties processing feelings but again his perception of what has happened in the past and what will happen in the future can be significantly impacted upon by the illness. It's difficult but try not to put too much stock in what he is saying while he is unwell (at least with regards to his own mood state).
My sympathies go out to you, it mus be horrible to see someone you love affected in this way. Try to keep reminding yourself of this point:
He is unwell, it affects what he says and does. Things will change when he is treated properly.
I have lost count of the number of times I have heard Depressed patients acknowledge how their thinking had been affected - after the Depression had lifted, not before.
If I can be of any further assistance to you in any way please let me know.