3) Puffins (Farne Islands - is his June/July)?
5) Rapeseed Fields
6) Swallow chicks
Not a wildlife photographer myself as I can't really photograph moving things, though I did photograph a baby toad last week. Must admit it was 'hand held.'
For the rest I think you simply have to go out and keep your eyes open, as I guess a lot of it is weather and topography dependent. I know for a fact that swallows are here, in the south, earlier than further north. Only a matter of days, but still ...
I remember seeing swallow chicks last year in Holland in June/July.
Poppies, are summer flowers, if I can trust my memory.
Rapeseed fields you can't miss when you're driving around. I saw some very yellow fields in the distance last week Tuesday, but too far off to see what it was. When in a car, that should not be a problem.
Puffins you photographed before; I think when you contact whoever organised that trip, they can tell you.
My advice would be: just go out and shoot nature/wildlife wherever you come across it. Don't miss a deer or a butterfly, because you're hunting frogs. You'll soon get to recognise the places/times which are most suitable for what you want.
Time of day (light!) will also play a big part, in what is out and about.
Not really answers your question, but I don't think you can pin a timetable on nature.