At the velodrome
For almost 2 seasons when I lived in England and especially during the time I was racing fixed gear, winter was dedicated to riding track.
I was lucky enough to have a brand new velodrome in the city where I used to live, Derby.
In England riding at the velodrome and doing cyclocross are the most popular ways to keep your fitness level up across winter. Indeed that worked out well for me too.
After about 6 practice lessons I managed to achieve and get my accreditation and be able to train and race indoor with my track bike.
Practicing at the velodrome gave me a lot in terms of skills, confidence and awareness while riding at close range to someone else wheels at high speed. I wish I was able to still do the same here in Italy, unfortunately there are not so many velodromes in the country available close to where I am.