to not want to leave our house?

[thestrawgrasper]

We signed a new contract in March. The LL has now said he wants to sell, and is having viewings (with notice, so not complaining about that). Can he do that in the first six months of our tenancy?

As far as I'm aware he can't break your contract if you have an assured shorthold tenancy (has to give whatever notice is in it) but can sell the property with you in it as 'sitting tenants' - has he said he wants you to move out?
A landlord did this to us when I was a PhD student, precisely nothing changed!

Sorry your LL wants to sell

Unfortunately I think as he's given notice he can sell (was your previous contract with him?)

It may take some time to sell but you can start looking (although I appreciate you don't want to) maybe for something with a longer lease?

Yes, he can. He has to honour your tenancy, however, till its end.