The river is lovely, you're right about the lighting, gorgeous

I love the stag but could do without so much space for it to get lost in. I would crop that back a fair bit and let us so the subject in close up. This is an example of where cropping it for print might be diffcult without it looking pixellated but cropping the 300dpi original to show on the internet would work fine as you are only showing 72 dpi.
Those kids are a pain but their parents should've been shot for letting them stress the deer by getting so close. Good image though and captures the story of what is happening as well as serving as an educational shot about how to behave with wild animals in the countryside.
Can't say the sunset does much for me, perhaps taken a bit too early. When the sun gets below the level of the cloud is when you get the really rich colours so worth thinking about for the future. I have never heard of the Richmond Park parakeets but they are ok. That was your quarry and you captured them on camera so good on you. Images don't do a huge amount for me but I am sure a twitcher would love em
Good images of a good day out.
Cheers,
Rob