Basing yourself there for at least a few weeks is fine, but coming and going isn't.
I don't know why people assume that everyone who has a second home lives somewhere that is plague-ridden, by the way and is bringing the virus with them. It doesn't travel on the outside of cars. After a whole year we still have the pitch fork brigade.
Posty husband is furious with the number of deliveries he is making to homes which are not usually occupied, and those which are occupied only Fridays to Mondays and he knows that how? I doubt all these second home owners are ordering parcels to be delivered when they are not at the second homes on Saturdays. Letters don't get delivered on Saturdays unless you have a parcel where I am, and we're lucky to even get a daily delivery. Also - you can go out on a Saturday, it doesn't mean you've gone back to your first home.