If you're going to do a lot of riding in the wet and in winter then the following might be of help. Good tyres are your friend. Make sure your tyres have good tread (it's the tread that displaces surface water) and I'd check out the reviews to see if people say they grip well in the wet. If you have decent tyres, then can trust them in the wet; they won't let you down. But there are some areas that are likely to be slippery when wet, so go carefully on them or avoid them altogether: manhole covers and white paint (zebra crossings and mini roundabouts are the worst), also roundabouts as they attract diesel spills, and they're hard to see in the wet. It's a bit different in the dead of winter (December - February), as the roads are seldom dry, and they can get very slippery with oil from engine and salt and yuck. In these conditions, you need more care than in normal wet conditions, and unless the roads are bone dry, I ride fairly upright and keep everything very smooth.