shed growers advice pls

ok peeps due to losing my grow room (was a spare bedroom) the only place I can grow is my shed I will have a space of about 1m by 2m now I am planning on using 50mm kingspan to insulate and 2x400w hps the shed is brick built any and all advice on this kinda build would be most welcome

Brick is a good insulator during the winter months and should hold in quite a bit of heat. This of course depends on your location, here is gets below freezing on the norm. I personally would test the area first, run your lights and make sure it does not get too hot in there, and see how long it takes before the room gets too cold. This will give you an idea of any supplemental heating you may or may not need.

You might also consider getting some coffee grounds from your local star bucks, they normally just give it away. Adding it to compost causes heat, but also raises humidity. You will need about 4-5 5 gal buckets a week, give or take. Only done this a few times myself before it got really annoying, but your tolerance my vary and it just might save your plants on those really cold nights. But you don't want to add this compost mix to you plants, just have a few piles of it laying around the room for easy cleanup when needed.

Edit: You might also want to get some Temp alert monitors. Here is a WIFI one I found: http://www.temperaturealert.com/Wireless-Temperature-Store/Temperature-Alert-WiFi-Sensor.aspx

Too expensive for me personally, but gives you a starting point. I'm sure there are much cheaper ones out there.