I will be honest - going by what I read there is no question about it.
If your mother lives with you full time - for more than a month - then it will be seen as a "Gift with reservation of benefit"
There is a more readable explanation here
I would draw your attention to this part
"e) Provision for old age, infirmity etc
The donor's occupation of gifted land is not a GWR, broadly, if it represents reasonable provision for his care and maintenance due to old age, infirmity etc, and results from unforeseen changes in circumstances (eg. a sudden serious illness), and the donee is a relative of the donor or of his spouse or civil partner (s 102C(3), Sch 20 para 6(1)(b)). The 'reasonable' test is subjective, and whether it is met depends on the circumstances."
As it oculd be a possible work around