It's a long story. But here goes.
When I bought my 147 from Smart Alfa they sourced them from Ireland, I believe. This meant that there were some variations in standard fitment: mine came with 16" Sport alloys (since replaced), leather upholstery, Bose stereo, and CD multichanger. It also had the Comfort Pack. I assume, perhaps wrongly, that these were standard for the Irish market. The Winter Pack however isn't standard in Ireland (Hibernia = land of Winter, surely?).
When I doing my pre-purchase research, my initial telephone enquiries of Smart Alfa assured me that the vehicle was "full UK spec.", and I think all their written stuff at that time sent the same message (I've chucked it out now). So when I turned up to collect the car and enquired why it didn't have a Winter Pack, I was told (in effect) to take it or leave it. Because I was £3000 in pocket, and the car had all the goodies I listed, and heated seats always remind me of incontinence anyway, I took it. I have had no regrets.
From what I gather the cars don't come from Ireland any more so presumably they are totally consistent with UK spec cars because that's what they are, even down to "standard" option packs. But you may want to check, and avoid an embarassing argument at key handover time.