Tiny brook- Chub & Perch fun.
Ty the attached link or just simply hop on the 11th page of the coarse species section ( the first ten is literally pike only :P). Make sure you read all four pages of the thread. There are some useful info there. I have once lived in Marlborough and the Kenneth there had some nice grayling in it as the gentleman before me mentioned in his post. Have you tried for perch with your flyrod? That can be good fun but definitely try to use a light rod. In winter try to fish downstream and use two or three nymphs. Dangling is the correct word to describe the action the best. Also, takes are gentle, if you can use a super long rod (10-11 footer) and just catapult/sling cast and make sure to be extra careful when approaching the swim you are about to fish. Chub prefers a mouthful even in the winter so use meaty flies (16 or bigger) and 18-16 should do for dace. Do not waste too much effort tying fancy stuff, hare's ear bug/spider, pink shrimp, pheasant tail nymph all work well. IF you need more info there is another thread I can recommend:
Winter chub - any tactics?
I am sure you will manage to get a grip of the winter fishing sooner or later.
Best of luck!
Pete