The opening scene (or one of them) is the main woman in a pool faking not being able to swim in order to get the attention of a man. They end up hitting it off and seeing each other. She doesn’t actually care about dating him, she is just trying to find out the truth about the suspicious death of his dead wife. The belief (or rumor) is that he killed her. Most of the movie takes place in England, where she is joined by an old man who is a friend that helps her throughout the movie. The older man stuggles to adapt to driving on the left side of the road (he’s from USA I think) and eventually him forgetting to drive on the correct side kills him. Near the end of the movie I believe she gets evidence the man did kill his wife and he finds out about this. Thinking she can’t swim, he takes her out to the middle of the lake in a canoe and throws her over.
This is an older(ish) movie that probably came out in the early 2000s and no further than late 1990s.