Section 21 notice after 8 years tenancy

We have lived in this house for 8 years, initially on an Assured Shorthold tenancy for the first six months, then it just rolled on (statutory periodic tenancy I think?) We never had another fixed term.

Always paid the rent on time. No contact with the landlord, everything through the letting agents. They didn't bother us much, annual inspections. Landlord very slow to carry out maintenance, only did what he absolutely had to. Letting agents gave us a vague impression that he was elderly and unable to afford necessary work on the house, so I sympathised to a certain extent. However I have just discovered that he is in fact younger than I am, lives in a prosperous area (I know the road well) and is the director of a property company, so presumably will own several properties. He should also know how to be a decent landlord!

We have just had an absolutely terrible year, a recent family bereavement, also my husband had to leave his job due to stress and pressure making him unwell. He has the promise of other work starting in September.

My husband had just had his last day at work and getting ready to finally relax a bit over the summer.when we had a phone call - the landlord wants to sell.

I agreed their 'sales colleague' could come round to value the house. He insisted on taking photos, even though I told him the house was not in a fit state. He assured me the house would not be going on the market immediately. He lied though (guess he couldn't help himself, that's what estate agents do, right?) as the next day the house was on Rightmove. The day after that I got a section 21 in the post.

Then for the last week there have been phone calls left on the answer machine from the agents every day. We were actually away for the week, as people often are at this time of the year. They shouldn't be surprised about that.

I do understand that the house belongs to the landlord, and so he has a right to sell. I just find it pretty disgusting that after over 7 years of regularly paying the rent and living there quietly they think they can chuck us out on 2 months notice. Yes, I know that legally they can do this. But it is just so inconsiderate. He must have known he wanted to sell, a heads up would have been appreciated. And as my partner is between jobs the timing is dreadful for us.

I just want to be left alone in peace over the summer, and also to have more time to find alternative accommodation. It is unlikely we would be settled somewhere else by the date they give, even without our current job situation. I'm still in shock over the bereavement and everything else that has happened this year. I really don't want to be spending my summer doing viewings either, or at least not yet.

What is the best way to achieve 1. more time in the property 1. no viewings, does anyone know?