Hi natalia88, the posting above from seajay recommends doing a search on enema uk to get a list of sources in the UK where you can order an enema kit.
Regarding the salt, I suggest you try Sea Salt (fine grain Sea Salt is easier to dissolve completely than coarse grain), but if not Sea Salt , any non-iodized table salt will do. Mix one teaspoon of salt per pint of warm filtered or bottled water, or 4 teaspoons of salt for a full 2 quart or 2 litre enema bag or bucket.
Once you become familiar with the procedure it's really easy and not really uncomfortable at all. It's uncomfortable only if you let yourself become constipated. The key is to avoid allowing yourself to become constipated.