Our cats tail flaps about all over the place when he is sleeping or resting, just wondering what its a sign of if anything?

Has it always done that?

Yeah almost every time he is resting or sleeping the end of his tail moves about, my guess would be its a sign of him dreaming or just enjoying his rest or sleep.

It's more than likely dreaming, bless him. One of mine chatters too whilst she's sleeping, she's obviously up to no good in her dream state, little minx!

Yes sounds normal to me, just relaxing and dreaming as you say.
Mine do that, and twitch and growl, they're so cute

Do you have a dog?

I say this, because I have 4 cats, One was an adult when we got her, and does not do this.

The other 3 were kittens, and all have been mothered by my dog, and wag their tails, when you talk to them, or fuss them, in the same circumstance as a dog would, but, being cats they do wag differently.

(One of them barks with a miow when you knock on the door)

Cat tails can shop emotion as a sweeping wag from the base similar to a windscreen wiper is generally a happy wag. If the tail is stiff and straight up, and sort of shakes a small bit that is more angry, or about to pounce. If the tail is floppy and the end moves, it is just dreaming and content.

I would not worry, just enjoy.
(Unless like mine it bashed you in the face with such a vigorous wag, cat being friendly but it still can hurt)

Had a dog 3 years before the cat, the cat has only been with us since November last year so nearly a year but he's nearly 2 years now.

So he has not learned off the dog then.

Sounds normal to me. My 4 do that when they sleep.