Many people will re-purpose chest freezers as fermentation chambers and they will place their carboys and buckets inside of them. Chest freezers do have their benefits as they are insulated and capable of cooling to any temperature (with the use of a temperature controller) wort would need for fermentation. They are often the home brewer's go-to for fermentation chambers for their ease of setup, but they aren't without issue (assuming you aren't going to dissect the machine):
- You are restricted to one temperature for all fermentation vessels inside
- You have a very finite amount of space, so expansion often means replacing with a larger freezer
- You need an external temperature controller
There are a lot of temperature controllers out there. One of the most popular controllers among home brewer's is the STC-1000, because it gives you the capability to control both heat and cooling (two power outlets, one for each). It does require a big of DIY ingenuity, but its cost, dual temperature control and the plethora of youtube and online tutorials make it one of the most popular.
Another temperature controller that is also popular is the Johnson line of temperature controllers (both analog and digital). The downside to Johnson's controllers are they are not dual-temperature. You can only use one for hot, or cold. Changing between the two modes is not difficult, but you cannot do it on the fly with the push of a button. These are popular due to their lack of DIY work required to get it up and running. You simply plug it in and off you go.
If you would like to go with the dual mode controller, you will also need a means to heat the fermentation vessels. I've seen everything from a hair dryer (not the most recommended), to a heat lamp, to a FermWrap wrapped around a single carboy/bucket. If you are not looking to ferment a lot of carboys or buckets at once, I would recommend a couple of FermWraps using a splitter, or a heat lamp.
Final thing to keep in mind is that you'll need to control the temperature of the fermentation vessel, and not the ambient temperature of the container the vessels are sitting in, as an actively fermenting vessel is going to be a degree or so warmer than the ambient temperature of the container it sits in.
If you'd like to stray away from setting up a chest freezer in favor of an all-in-one package, your options are very limited. I've heard a lot of good about MoreBeer's Conical fermenters (not sure whether or not they ship to the UK). The difficulty you're going to run into when searching for a one-size-fits-all solution is that they are going to quickly rise to prices beyond many home brewer's budgets (as you can see with the aforementioned products).
When you ferment your wort, an actively fermenting wort ferments higher than the ambient temperature the vessel sits in. The actual temperature it ferments at will depend upon the aggression of the fermentation (how high of an OG), and what phase the yeast is at. Often times what people will do with their temperature controllers is take the temperature probe, place it against he side of the fermentation vessel and tape 2-3 layers of bubble wrap over the probe, onto the vessel to ensure the probe reading the temperature of the vessel and not the ambient temperature around it. If there's more than one vessel fermenting at once, it's best to assume the vessel that is being probed is the same temperature as the others, assuming all fermentations are identical worts with equal pitch rates of yeast (e.g. same 10-gallon batch split into two 5-gallon vessels with 1 package of yeast in each).