The club has advised in the past about using mudguards during the autumn/winter/spring period. The advantages of using mudguards are simple yet very effective. The full wrap around type are the best as they save spray from hitting the rider behind which means the rider behind can stay directly in the slipstream better thus ensuring the group can stay closer together and not be spread all over the road. They also help keep your backside a lot drier which I’m sure you’d agree is a lot more comfortable.
There are several types of lightweight mudguards available for road bikes and are available locally. Fitting them is fairly straightforward or if you're not confident in taking on the task, your local bike shop will be happy to oblige.
While you're at it, It's also a good idea to fit a red rear light. It's the law if you're night cycling and improves your visibility to motorists and other road users during the day. Again there are lots of styles and types available, even ones that fit to your helmet. LED lights are best because they're brighter and have a much longer battery life. Your local bike shops carry a good range of lighting.