ChasG, you are certainly not the first or only student pilot in this frustration, at the contrary most must have been through this to some degree. Myself have been very lucky, though, in this respect.
Do not be put off by the oncoming winter. I am puzzled about the mention "too cold to fly", cold is only good for flying: cold air is denser, thus improving performance of wings and engine alike. Drag will go up too, yes, that's the counterpart, theoretically. The nicest is however that cold air is generally very stable, far less turbulent than on those treacherous days of summer that only bring unexpected turbulence and haze.
True, many days will be spoiled by low clouds and/or poor visibility; and grass runways may get too soaked and thus closed. But whenever you CAN fly, it will be great flying. Count on booking twice for flying once, as a crude rule of thumb.
A few snaps to make you drool:
http://users.skynet.be/fa348739/image/IMG_6778.JPG
http://users.skynet.be/fa348739/image/IMG_6779.JPG
Yes that's me, on some of my very early solo flying, photography courtesy of my instructor.
Do not be put off by the oncoming winter - but do prepare your thermal underwear.