I currently run the setup as suggested by Pittsy, but with two 25W Aquarium heaters as that's what I had, only one tends to be on at a time though really, only both if it feels it's got really cold, and a digital thermometer sanitised on brew day and dangled into the FV, the whole lot then lives in my garage.
And apart from last weekend when the wort seemed to spike up to 29°c it has remained a steady 22°c all week so far including over night when the temperature has really been dropping around my way.
I use a large trug from Homebase, £6.49 and it's once the FV is sat inside it filled up to about the 3 litre mark on the outside of the FV.
I'm considering a bit of planning ahead and building and STC-1000 set up just for the heat side for now until I can use the heat and cool function with a fridge, need to start gauging swmbo reaction to the brewing take over first.