We request 45 hours of Spitzer IRAC and IRS time for low-impact Target of Opportunity targets. The targets will be very-late T or Y dwarfs found in the UKIRT Infrared Deep Sky Survey (UKIDSS) over the next year. Candidate very cool dwarfs identified in UKIDSS will be confirmed and classified by near-infrared spectroscopy at Gemini Observatory. Dwarfs of type T8 or later (of which there are only two currently published) will be submitted for IRAC observations. The coolest of these, those estimated to have an effective temperature Teff of 700K or less, will be followed up with IRS first-order short-low spectroscopy. UKIDSS has already found the latest-type T dwarf to date in a search of a 190 square degree area, a T8.5 with Teff approximately 650K, and an estimated age and mass of 1Gyr and 20 Jupiter masses. Over the next year a further 800 square degree area will become available, and we anticipate obtaining IRAC images of around eight 500-800K dwarfs, and IRS spectroscopy of four 500-700K dwarfs. Measuring the complete energy distribution of this new cold low-mass extension to the sub-stellar sequence is important to do while we have Spitzer's full cryogenic capability.