In the UK, you can offset the costs of the office space against tax - proportioned heating and lighting etc. But if/when you sell the property you need to be aware of possible Capital Gains Tax liability on the office space.
In my postgrad days I had two cats. I used to practise my presentations on them. They found it amusing and I could work through the irresistible temptation to talk a character out of Wacky Races so that I could concentrate properly on the day.
I now have a dog. Dogs are good for fresh air and exercise too and you meet other humans too.