The rule of thumb I'd use is if the target traffic is UK based, then buy the UK. If its overseas based, buy the .com. Lonnwedding woould be more applicable to UK people wanting to get married so buy the UK.
The reason is that Google defaults to google.co.uk to anyone searching from the UK and vice versa. A .co.uk site hosted in the UK will get much better SERPS on google.co.uk than google.com, and this is wher ethe audience is. If you want US tourists to visit then buy the .com and host it in the US.