This movie is cute, mindless entertainment, and has fabulous views of the Highlands. In fact, one review I read said that the Scottish scenery was the best part. Anyway, scenes of Glen Coe, Glen Finnan, Eilean Donan Castle, and Tobermory on Mull are the most recognizable. Also, in the credits, the location manager is Duncan Muggoch who had the same job in MOTG. I also caught the red-headed gilly as an extra.
Are you near Cliveden House? The credits listed that as a location and, when I googled it, it showed being just north of London and was probably used for some scenes which are in a castle interior. The exterior is Eilean Donan, just outside of Skye, which was not surprising as there are lots of films made there. All lovely locations.
I saw one of the main characters being interviewed and he said that they had being filming in Woodstock which is just north of Oxford. I've also heard, locally, that they were filming at Broughton Castle, which is about 3 miles from my house. BC has being used in a couple of films in the past - Three Men and a Little Lady and Shakespear in Love. OxBo