The Xperia T2 Ultra is not even listed on Sony Mobile UK’s website, so it doesn't look like it's in the company's plans for Great Britain. Even so, according to Carphone Warehouse, the new, extra-large 6-inch smartphone should be available to British customers sometime in April. Clove is another retailer that expects to have the T2 in stock starting next month, saying that this will cost around $500 (£312).
In case the T2 Ultra never makes it to the UK, maybe you’ll be interested in getting the smaller and cheaper Xperia M2. Announced by Sony in February, the 4.8-inch M2 should be released in the UK starting next month for around $370 (£228). Clove, Carphone Warehouse and various other retailers will stock the Xperia M2.
Both the Xperia T2 Ultra and Xperia M2 will run Android 4.3 at launch, but Sony is probably planning to update them to Android 4.4 KitKat later this year.
sources: Handtec, Carphone Warehouse (Xperia T2 Ultra), (Xperia M2), Clove (Xperia T2 Ultra), (Xperia M2)