I very much doubt you are the only one out of 6,000 who have got hearing problems. I dont have much experience of people who sign but the little I did have, it seemed to me that signing is more used for deaf to deaf communication and for public use, at concerts, meetings and so on. I know more hearing children are learning it at school now. Lipreaders can ask for people to remove their masks. Has your surgery got any kind of text phone facility and have you? it sounds as though your practice manager isn't being helpful....maybe advice from a charity for deaf people might help you get this sorted?