I have a got sky q with sky, and I pay for 4 pounds for my Ultra HD every month. So do this mean I have got ultra HD subscription with my sky q and watch on my sky q

Yes, if you are paying an additional £4 per month for Ultra HD with your Sky Q subscription, it means you have access to Ultra HD content on your Sky Q box. You will be able to watch programs and movies in Ultra HD, provided that you have a compatible Ultra HD TV and you're accessing content that is available in that format. Just make sure that you are tuned into channels or content that support Ultra HD to take full advantage of your subscription.