Winster has a pretty good bus service - about 6 trips per day each way (Monday-Saturday) but no Sunday or Bank Holiday Monday service. (Nearest Sunday buses: Darley Dale and Youlgrave).
Some Winster buses serve Matlock's Rail/Bus station, but not all. All Winster buses call at Matlock's old bus station behind the Co-op, now shown on the timetable as "Bakewell Road".
Buses on route 172 are run by Hulleys of Baslow: see the Interactive Timetable. Beware that Hulleys take quite a relaxed view to timekeeping: buses can leave two or three minutes before the printed times.
Hulleys' website does not show service interruptions (eg in snow), but they reckon to notify these on their Facebook page. They also say they inform Traveline as early as 0630 each day: these updates should show in the Traveline results. Or you can always try calling Hulleys on 01246 582246.
Note for ramblers fancying a one-way walk: several buses from Bakewell come via Youlgreave. The late-afternoon bus also visits Middleton-by-Youlgreave.
To/from Sheffield, the fastest option is the 218 from Bakewell - taking about 45 minutes. Many services start/finish at Matlock, and can be picked up at Darley Dale - but most travel via Chatsworth, making the Bakewell-Matlock leg rather slow. From Matlock, there is little difference in journey time between the 218 via Bakewell and the x17 via Chesterfield - both take about 75 minutes.
Bakewell and Eyam Community Transport run services for “local elderly and/or disabled residents and to visitors to the area”. They operate Dial-A-Bus services from Winster to Matlock, Bakewell, Alfreton, Buxton and Chesterfield on certain dates each month, as well as a series of day trips further afield with pickups in Winster. They also hire 16-seat vehicles to community groups at reasonable prices (Secret Gardens use them for their Park & Ride service, for example).
Beware the "Derbyshire Wayfarer" day ticket - once very useful, this is no longer valid on most Transpeak Services.
There is a useful bus map available in PDF format.
The Transpeak service runs hourly for much of the day on the route Derby-Matlock-Darley Dale-Bakewell-Buxton and sometimes on to Manchester. But be warned that punctuality can be very poor.
National Express run a daily coach from Matlock to London - leaving from the bus/rail station at 8.25 each morning (at the very moment the first bus from Winster is arriving outside the Cooperative on Bakewell Road) and taking about 4½ hours. The return trip leaves London around 4pm. There is a useful National Express service from Chesterfield direct to Luton, Heathrow and Gatwick airports about five times a day.