Hi Paulsgirl, sorry to hear about your illness, hope you'll get through this.
There are advantages and disadvantages to putting properties in joint names.
The advantage would be that if either of you died there would be no need to extract a grant of probate to your estate in order to deal with the properties as they would automatically go into the sole name of the survivor on production of a death certificate. Therefore the cost on death is less ( and may be no need to extract a grant at all assuming all other assets are also in joint names).
The disadvantages would be that you would have a cost now of the transfer ( although I would estimate this to be much, much less than a grant of probate), legal fees and some outlay such as land registry fees on the investment property ( although none on the family home).
Also sometimes for tax reasons it is better to have investment properties in the sole name of a lower-earning spouse to take advantage of all their tax credits( something I read recently on AAM but check with your accountant who does your rental income returns).
Also in the event of a break up, tranferring property into joint names can lead to a presumption that both become equal owners despite one spouse having contributed more.