If you cannot predict EVERY pairing in the first 5 minutes I'd be pretty surprised. Including the one involving the maid of the "evil" mother who is constantly spitting in the women's beverages but never gets the pleasure of having her special ingredient consumed. I'm not really sure what it is with these films - it's as if producers are under the impression that hot lesbians cover a multitude of cinematic sins. There's likely some truth in that - though in this case not enough to get it above lightweight status.
It's hard to tell if the acting is making the extremely commonplace writing better, or if both are weak. Technically it's shot well with some nice backdrops and the two women (actually most of the women) are well served by the cinematographer. I've read it was based on a book - I'm sort of suspecting this just wasn't a great adaptation to the screen.
I almost walked out - but having nothing else particular to do I stayed. Once the two women get onscreen it's tolerable overall. I'm not sure I really laughed, and with the outcome less in doubt than usual there wasn't anything interesting story wise. The two female leads are good enough along with some of the scenery (Oxford in particular comes off looking like a nice place to visit) made it a passable morning diversion. But if you're looking for a truly good in an English language romantic comedy try something else, perhaps - "Definitely, Maybe." Then find your lesbian film fix somewhere on the internet if you're that desperate.
Reading the variety review it seems the two women also starred as a couple in another recent film. I'll probably see if it's available - perhaps that's better...