Good call, guinea pigs are great! They can live indoors or outdoors (if outdoors must be well insulated and dry in winter). I prefer to keep mine indoors as they interact with the household more!
The main thing is to make sure they have enough space, nearly all the cages/runs sold in Pets at Home are too small for a pair of piggies, they need 60cms x 120cms as a minimum and ideally more. Make sure too that your run is well-proofed against foxes...
For bedding you have a number of options. You can use torn up newspaper but it gets smelly very quickly. Shavings are an option but not great for them due to the dust and also sharp bits can hurt their claws. The options usually recommended by guinea lovers are either a paper based bedding like Equizorb (a horse bedding you buy in bulk) or I use something called 'Back to Nature' which is paper pellets and comes in more manageable sacks, OR you can use an old fleece blanket, which you then shake out daily to remove poos and change regularly once it gets damp.
Feeding wise they eat pretty much any raw veg (there are a few exceptions which you can google) and this means you can reduce household veg waste to almost nothing as they'll happily polish off things like salad which is past it's best or veg tops or peelings. They should also be given a balanced/fortified pellet feed daily (not a muesli feed as they'll pick out the bits they like and leave the rest) and plenty of hay.
Care wise they are easy to look after aside from cleaning out the cage regularly, you should handle them daily to keep them tame, some long hair breeds may need light grooming to prevent tangles and also you may need to trim their nails occasionally (or get a vet to do so!).
Pictures please when you get your piggies!