Dad recently diagnosed with terminal lung cancer

I found out earlier this week that my Dad has been diagnosed with terminal lung cancer which has spread to the lymphnode and bones  It's all come as such a shock, as he was taken into hospital with mild heart failure last month and then after he had a CT scan they discovered he had lung cancer and its all escalated from there. I just can't believe what is happening and how quickly it has developed and spread... he was only in hospital a year ago with gallstones and there was no sign of cancer then  I'm absolutely devastated and feeling every emotion that you can think of. They have advised that no treatment will be given due to him not being very mobile and his health in general. He isn't in any pain currently... we have been advised that only pain relief will be prescribed when the time comes. My Dad lives by himself and he is hopefully going home next week, after they have delivered equiptment for him (he's desperate to get back to his flat and to feel some normality). I want to spend as much time as I can with him and make the most of what time we have left (we haven't been given any idea in regards to life expectancy). I'm already exhausted with juggling work and visiting Dad. Has anyone got any advice on how to get the balance right? I hate the idea of him being on his own for long periods of time.