Yes, waiting lists for NHS counselling are terrible
. Does your employer offer anything - I know where I work there's a free counselling service for employees, but I work for quite a big company.
Breaking down your work and allowing yourself a micro-break sounds like a good idea, it's a shame it hasn't worked this week but don't give up on it.
It's easy when you've had a couple of bad days to then write off the whole week and think it's not even worth trying to be productive, but you have to try and treat each day as a 'fresh start.
I shut my cats out of my working space - could you try that, or will your cat scratch your door to pieces? Or you could make playing with your cat a 'reward' after 30 mins of concentration?
I've tried to minimise things that distract me in my working space - I have my laptop and a radio on my desk and that's it - nothing else in my eye-line at all.
I don't think you should feel bad about seeking your manager's support when he is back. Your perception is that you are always the one in the team with stuff going on, but that might not be your manager's perception - you don't know what other members of your team might have going on in the background, there might be others who are struggling as well.
Ultimately it's part of your manager's job to support you and a good employer will recognise that in these exceptional times, people will have more wellbeing issues than normal - it's nothing to be ashamed of. Managers should be receiving training and guidance on how to support homeworkers who are struggling. It's better to speak up and say that you're concerned about your productivity than to let the issue get worse and worse.