I read recently that the new engine has been postponed for some time apart from the on new Golf. For example, the facelifted Leon due soon does not offer the new engine.
The only reason you cannot have a DSG version in the UK is because, for some weird reason, SEAT UK didn't want it. If the 1.5 engine does appear on other models there is no reason to think that they will not take the same attitude. There are big delays on the Tsi engine because of unprecedented demand in all the VAG cars, it is not an issue because of the DSG.
If SEAT UK changed their minds, a TSI/DSG could be back on the list tomorrow. Incidentally, you can specify a TSI/4 Drive elsewhere in Europe.