Cocker spaniel waking up very early

By eventually giving in to his fuss and scrabbling at the gate you are teaching him that his fuss and scrabbling work and you respond to it.

Hard to do, but ignore it. He will realise that it doesn't work and that he has to fit in with your routine, not the other way around.

Routine is everything with dogs. If he knows he has a last mooch around the garden and a wee before you go to bed and then, when you rise he has the same opportunity to do so then this is what he will expect, he'll feel safe and comfortable with that and get used to.

Sounds like having a new baby. Give him a teddy and a dummy.

He wakes up at a time that’s natural for him and wants to play, like a young child. It sounds as though you really shouldn’t have got a dog.

Apart from taking down the gate and opening the house up so that he is free to wander, I can’t think of anything.
We dog sit and she wanders around the house at night, sleeping where she wants, without waking us up, she usually comes into my room at 7am and snuggles on the bed until I get up.
Maybe your Dog is bored and feels trapped?
Puppies and older people ? Hmmmm

He probably wants company. Dogs are pack animals.
I’m afraid to say that when our (half cocker spaniel) puppy did similar - barking and whining in the kitchen - I eventually just let her sleep in our room upstairs.

She would then (mostly) keep quiet until she knew one of us was awake. I don’t know how they know, when you haven’t even opened your eyes properly, but they do. Or she did anyway, and a previous dog was the same.