Time...

Hello all

I'm trying to get some sort of vague idea of time left for my 77 yr old mother in law. 

She was diagnosed with mouth cancer in August last year (2016) and had part of her tongue and jaw removed in November 2016. She was advised not to have radiotherapy.  She has other problems - high blood pressure and COPD between by the most prevalent. 

A new tumour has appeared in her neck - large and inoperable, and she is now terminal. 

No one can give us any idea of time frame. I totally understand this - depends on person, cancer, etc., etc. 

I'm just wondering if anyone has experience with similar with their loved ones; we're planning nice things to do together -  we'd like to take her to a cottage or something for a break for example. 

Its an awful thing to think about and ask others in here but I thank you in advance for any help you can give, and I totally get that any answers will be guesstimates at best. 

Thank you