BHG...if you can afford it right now, get some kind of rain suit..it doesn't have to have HD written all over it. Go to an outdoor store and get the best rain gear you can afford. If it's breathable/waterproof like Gore-Tex (other companys have similar materials), so much the better. If you get something made out of plastic, you won't be able to tell whether you are wet from rain or from sweating inside the plastic material, even in cold temps. Anything cotton is absolutely useless to you in cold or wet conditions unless you can keep it totally dry, and if wet will actually suck the heat right out of your body. Great in summer, but not good in cold. Fleece or polypropelene garments will not absorb water and will keep you warm, even when they feel wet. Cotton socks are also useless items, no matter what time of year it is. Invest in a couple of pair of good wicking ski socks (I like them because they will go over the calf and stay put, not wadding up in your boots), in either a midweight or lightweight. They will last you for years! Second best choice is a good hiking sock...NO cotton on your feet. Some boots make a fashion statement, and that is fine, but if you want function over form try to find a good pair of comfortable boots that are also waterproof...these are not easy to find. One that is comfortable riding and walking, and is waterPROOF without any treatment of oil, etc, is Cruiserworks Boots. The Lady Defenders are not bad looking, and will be the last boots you buy for riding for years to come. Gloves are a compromise between warmth, grip, and dexterity, so you can feel the switches, grips, etc.
If all else fails, dig out some of those wool things you have...that's what I used for years hiking in cold, wet, snow...it will keep you warm, even when wet. Also anything with thinsulate for warmth. For a hat to wear when not wearing the helmet, a fleece balcap, or wool felt brim hat, or just good old fashioned wool 'boggins.