Hello, I am Keith, one of the experts on Just Answer, and pleased to be able to help you with your question.
I would suggest that you tell your solicitor to take a running jump, that he can whistle for his fees and report his antics to the Law Society. Complete the Land Registry (LR) forms, submit them and that will sort out the Joint Tenancy. Many people do not realise that land can be transferred using a LR Transfer and it is far cheaper than normal conveyancing. Mark you you must be sure of the title. I have done it once to transfer a holding between two companies within the same group.
You are correct that when you die and your husbands 325K band is unused you inherit it giving a possible exemption of 650K. However, the law is changing regarding the family home. For the period 2017 - 2020 such a bequest to children has an increased exemption rising progressively to one million over this period.
It is a good thing you got in touch with the LR and the Probate Office direct which exposed some possibly incorrect professional advice.
I do hope that you have found my reply of assistance.
Thank you for your support.