Dogs - and cats

I want a dog. It's really the last of my big dreams yet to be fulfilled - apart from the artist one, of course! I'm planning to take some time off work in June or July (or it might have to be August!) to travel through to Inverness to the dog rehoming centre there and chose a dog, or perhaps two. I worry a lot about leaving a dog/s at home on their own during the working day - though I'll come back at lunchtime to walk them - and feel that having two might help them keep each other company. I'm going to take advice on this...
The last of my four cats - and the first, being the mother of the other 3 - died in April. She, Bridie, was on medication for hypertension which the vet said would have helped cause problems with her kidneys, which is what appeared to be the cause of her final illness. She had a stroke last July and wasn't expected to survive. I researched on the internet and found lots of mentions of cat who'd survived strokes. I gave her two weeks to see if she improved and her progress was so marked, I gave her longer, and then longer... and then longer...! In the end she was disabled - problems with her back legs, a bit deaf and not able to see properly - but it never felt right to have her put down. She was back to her normal, stubborn self soon enough and seemed to be perfectly contented just sleeping, eating and... well, using the litter tray! I knew it was only a matter of time before she gave up the ghost but I don't think I really expected her to live another 9 months. Without her hypertension, she would likely have lived even longer. I don't have any recent photos of her but will post some of her last July. She was just a couple of weeks short of her 16th birthday when she died.
16 years...! What a long time to be responsible for an animal. And I want to start again with a dog?!