Try pickandmix seeds to get a selection of 2 or 3 different varietes (assuming you'll be planting more than one) to see which work best. The average Skunk is renowned for being easy to grow and will most likely produce a fair crop with enough nutrient feeding, however they can certainly stink (as many strains do) and (guessing it's a covert operation) may cause a problem. Just make sure you have your planting area well chosen and secure.
Those I suggested would be worth a try, as well as JoNny Pot sMokeRs suggestion of Top 44, even look into Swiss, Canadian and other high altitude strains as they're often suited to the cold. Dr Greenthumb has a super early Iranian Indica. Apparently even Arjans Haze 2, 3 and Blueberry do well over the summer here.
Ideally, you want:
- Somewhat loose bud structure (to reduce the chance of devastating mould in flower).
- A short flowering period combined with conformation of being an outdoor strain (Northern) from the breeder.
- Security suitable and inexpensive seeds if you're inexperienced, most breeders are quite decent, despite prices (eg Mandala are great)
Keep me posted with you're decision and progress, best of luck.