We had a leak on ours. The spout screws off. Think you turn it in the opposite direction. Our O ring was fine and had a hairline crack in the thread. We managed to fix it by melting the crack back together with a soldering iron as suggested by someone on this forum.
Hi, if its the O ring you can buy a selection box of O rings from the poundland type shops, I keep a box in the caravan its helped me out on a couple of occasions. and guess what they,re only £1
Hi, the plastic nut should enable you to release the spout but can be difficult to get at as it may be recessed into the work top. so you may need to release whole tap assembly by removing the 4 screws at each corner of the tap plate [ they are under plastic caps ]. then you may have enough pipe to allow you to lift taps to get at the nut, if not you will have to disconnect water pipes at the underside of the taps then whole assembly will be in your hands for a good inspection and will make any repair easier to do.