The typical asking rate per listing is in the $250's per square foot per year. The Norwich region is seeing a a boost in rates. In the last 3 months, the median rate rose $253 per sqft per year.
In the last 90 days, 11 listings have been made available, which means spaces are probably going fast. You'll want to be prepared to make an offer immediately. About 100% of the listings in the Norwich are subleases, so you might be able to sign a shorter term by taking over a previous lease. There aren't many listings below 2,000 square feet on the market, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 2,200 sqft. Most buildings in this market are close to 2 stories. Most buildings in this area were built in 1895 and are Class A.