Hi and welcome!
I would strongly recommend to put your hutch out of the weather into the outer house during the colder months. They will still need heating.
Please also make sure to place your hutch away from the worst of the sun and any heat traps in your garden in summer. Guinea pigs can suffer heat strokes, too!
How big is your hutch? Two guinea pigs need a minimum of 2x4 ft ground space per floor.
With members from all over the world, it is very helpful for us all in giving you the appropriate advice and recommendations for you part of the world straight away if you added your country, state or (for the UK) your county/general area. Click on your username on the top bar, then go to personal details and scroll down to location. Thanks!
Have you considered getting your guinea pigs from one of our recommended rescues? They are by far the safest place to get guaranteed healthy, carefully bonded and not pregnant piggies from, so you can avoid neatly all the usual pitfalls that await the unwary. The rescues we have listed are all piggy savvy and will not pair you up with piggies that need an experienced home. You will also get support during the settling in period as well as throughout the whole life of your piggies.
https://www.theguineapigforum.co.uk/threads/boars-sows-or-mixed-pairs-babies-or-adults.108944/
https://www.theguineapigforum.co.uk/pages/guinea-pig-rescue-locator/