I assume the smell is what gives you away the most with such a small grow, and not the large amount of heat that "factories" give off. Apparently there are helicopters detecting grows that way. LED's could grow 2 without any heat, right?
2) Getting done if you are.
Assuming there is 2 of us in a house (1 each), with no previous criminal record.
Do they take things like your education and your job into account?
Nobody's going to come after you for two plants lad, you'll barely get an ounce smokeable from it anyway, and you'll be lucky if you make it of any decent potency on your first time. Stick it in a basement or hide it in plain sight in a greenhouse. Plenty of weeds and other common plants have a stronger smell.
What you want to worry about is GCHQlad tracking you down for posting a thread about if you'll get caught for growing weed or not.
The smell can be dealt with quite easily by keeping the plants in a sealed tent and using an activated charcoal filter on your exhaust fan. Smoking smells in your house can be neutralised with an air ioniser. Most of the time, a small grow will only merit a fine or a community order on a first offence. There's an obvious distinction between someone growing a couple of plants for personal use and a commercial grow. Don't keep anything in your house that might suggest that you're dealing, or evidence of previous grows. Scales, baggies, large quantities of cash or diaries and photos of previous grows can all be used against you.
Thermal cameras will spot thousands of watts of growlights, but they won't see a little 400w HPS in your airing cupboard. 99% of the time, people get caught because they're indiscreet. They blab to their mates, their neighbours see them carting out bags full of trimmings and root balls, they have a loud party or a domestic that the police get called out to. Keep your mouth shut and keep a low profile. Don't tell anyone that you grow and don't show off your stash. Don't leave paraphernalia lying about in plain sight and try to make your home and yourself look as respectable as possible. Only break one law at a time - a lot of people get busted because of something as trivial as their tax disc running out.
Have a look on the UK420 forums, there is a ton of really useful information there about small-scale growing.
