To my knowledge the ultimate ticket doesn't give you any extra hours at the parks, you simply get a 14 or 21 park hopper, with access to Pleasure Island, the water parks, and Disney Quest for as many days as you like in that 14/21 day period thrown in.
You do get extra hours by staying at a WDW resort. This is called Extra Magic Hours.
You get 1 hour in the morning and up to 3 hours at night at selected parks & water parks (different ones depending on day of the week and time of the year, you can look them up on the WDW website).
At morning EMH, you just have to show your "Keys to the Kingdom" card (that's doorcard to most people

) when entering, and for the evening ones you pick up a special writeband at select locations in the park from about 3 hours prior to the start of EMH, these wristbands will then be checked before you re allowed on any rides after EMH starts.
I may get corrected and told there is something special for UK guests with ultimate tickets, but I think that's how it works.