Sounds like to me that it would be more expensive to have it purchased here in the US and then shipped to the UK. It may be more worth your while to just purchase it where your from.
As for the GoPro 2 Vs. the 3 or 3+. Honestly its going to depend on what your looking to do with it, and what options your looking for. If you just want to document your rides and save them for your own personal viewing and maybe putting them up on YouTube or some other social media. Then I would say thats the way to go. Now if your a budding photographer/videographer like like James. Then you may want to have the higher end stuff.
Now some food for thought. The GoPro company is developing equipment so quickly that whatever you choose to purchase will likely be obsolete with in 6 months time. Or even sooner. I say just go with the GoPro 2. Its easy to use and doesnt really require alot of extra accessorizes to get its full potential. I have just the GoPro HD Hero. And I think it works just fine. It produces a very nice video quality. Here is an example. Just be sure that when you go to watch the video you select the highest quality HD before viewing.