So, now you have your rats, where do you keep them?

There are two main options for the housing of rats: cages or tanks/aquariums. In general, a cage is preferable over an aquarium for a number of reasons. The main reason is that tanks don't allow for good ventilation and rats can suffer from respiratory problems at the best of times. Because of this, you will need to clean a tank much more often than you would a cage. Also, tanks don't leave much space for adding toys. I would only use a tank for nursing does or young babies. Very young rats should not be housed in cages as they can easily get their foot caught in the wire and cause injury and also, they'll try to climb which, if they fall, may prove hazardous for a baby. A tank will be good until the babies are weaned and ready to go.

In the UK, Pet cages do some good cages suitable for rats. Just go to 'small animal cages'. The critter series are appropriate for rats. Also, this site has reviews from rat owners for many of the popular cages, so is worth a read if you're not sure which cage to go for.
Aside from any vet's bills, the cage will be the biggest expense in owning a rat and it's worth spending a bit of cash and getting something good than scrimping and having to upgrade the cage later anyway. Steer clear of cages made from galvanised metal and these tend to smell bad after a time and are almost impossible to ever get smelling sweet again!

For litter, most pet shops will advise using woodshavings, but these are not suitable for rats. Wood shavings contain oils called 'phenols' which damage your rat's respiratory system, so they should not be used in the long term. There are far better options these days. Paper based cat litters are safe for rats. Two brands which work fine are 'bob martins paper based cat litter' or 'Bio-catolet'. They're essentially the same thing, but Bob martin's is cheaper and seems softer. However, these are the only two brands of paper based litter which are suitable. Others may be paper based, but can have oils added to make them smell nice, which means they are not suitable.
Bob Martins should be stocked at ASDA, and Bio-catolet is available in Tesco as well as other places. Always make sure you only use PAPER based cat litters. Clay based litter could be dangerous if your rat ingests it. There is also a product called 'carefresh' which is safe and seems to be becoming more common in pet shops in the UK.
A very popular bedding at the moment is a brand called EcoPetBed, which is corrugated strips of cardboard intended as horse bedding, and it comes highly recommended. Unfortunately, it isn't very easy to source in the UK at the moment.

Rats love toys and are very intelligent so you should provide them with things to keep them amused. They love hammocks and no rat should be without one! Once they have it, you won't be able to get them out of it. I have several, so that when one is in the wash, they still have another to go in. Hammocks can be purchased at acrorats.co.uk and Hammocky Hammocks If you have rats that like to destroy everything you put in their cage and don't want to spend money on something they will chew to bits a few days later, you can make your own hammocks out of towels and some clips.

Rats don't really enjoy wheels and most available running wheels are not suitable for rats. They're either too small, or the ones that ARE supposedly rat safe aren't. The only recommended wheel for rats is the 'Wodent Wheel'. These wheels are designed specifically with rats in mind and are 100% rat safe. However, you'll find that most rats will sleep in the wheel rather than run in it. Seems that you need to introduce rats to wheels while they're young for them to ever use them properly