Hi,
In short, no. It's not worth all the expense to bring a Smart car over. The reason is it's a normal 'bread and butter' car, nothing special and there's thousands of them available here. Your's would be a left hand drive, imported vehicle so would be more expensive to insure as compared to a UK RHD version.
If you had something 'interesting', like a classic US muscle car, a very rare modern car/variant of a popular car, something worth a lot of money etc, then it becomes much more worthwhile to bring over. Within the family, we've imported ourselves a 2003 Ford F150 Harley Davidson Anniversary Edition truck of which at the time there were only perhaps 10 or so in the UK, one of which David Beckham had (we had ours before he got his!) For a few months a couple years ago, purchased another one of them but sold it within a few months to free up some capital for a business aspect. There's a big scene here in the UK for 'interesting' American cars, but Smart cars from abroad have next to nil interest.
Sell your example for as much as you can prior to moving here and as mentioned by KFDancer, buy one here!
Cheers, DtM! West London & Slough UK!
P.S - had two Smart cars for advertising purposes one time! great fun little cars! We gave two of our female staff members (at the time) one each to take home each evening as a company car and got in plenty of potential interest in our company and products! Might have to do the same again soon!