The first vital thing that you need before purchasing a horse is a stable - that is plenty big enough to house your horse. The stable will have to have room to provide: a decent sized bedding area, room for food and water and plenty of space for the horse/s to walk around the stable with ease.
Next you need all of the equipment to groom and clean your horse. Equipment: hard and soft bristled brushes, hoof pick, shampoo and conditioner, sun lotion all of these are available at most equestrian shops.
To be able to ride your horse you need a saddle that fits your horse comfortably and also a bridle that fits the horses head. Stirrups come with the saddle however it is better to go to the local horse shop and buy 'Safety Stirrups'.
For winter it would be best to purchase a rug for your horse as it will keep them warmer than without a rug on.
For further information on care for your horse visit: http://www.horseandhound.co.uk/horsecare/