Anyone going for more than 2 weeks or going twice within the year consider annual pass for universal/IOA. Cost about £100 but you get unlimited admission for a year, free parking, discounts, 15% off food & drinks, 20% off merchandise, 45% off VIP tours, free addmision to special events plus more.
Best thing is after your 1st year you can renew at a rate of £55((+tax) about the cost of 2 days.
The pass we have now we bought 2 years ago buy 1 year get 1 free (2 years for £100)
Seaworld do one similar for about just over £50
No good for a 2 week holiday but ideal for us.