Tavistock is on the A386 from Plymouth to Okehampton, the B3357 from Princetown and the A390 into Cornwall It used to have two stations on different lines but is now dependent on buses for public transport. 
Regular trains run to Plymouth from London and Elsewhere (A Change in Bristol may be needed). The nearest station is Gunnislake, which is on the Tamar Valley branch line from Plymouth. It is around 4.5 miles from Tavistock, with direct buses between them. There are currently plans underway to extend the Tamar Valley line all the way to Tavistock, though this won't be until 2012 at the earliest. From Plymouth, take buses 83, 84 or 86 to Tavistock.
Walking will suffice for Tavistock itself. It's a great centre for a holiday, particularly if you have a car. A few bus services run through the town from the main station to housing areas and along Plymouth road and Whitchurch Road, but the town centre is very small so can be walked easily.
Specific sights are not part of the town's appeal, it's just a thoroughly pleasant market town with good shops in a fine position.
The Pannier Market In the centre of the town, full of interesting stalls during the daytime.
The Viaduct Above the town, is also the start of a pleasant walk along the old railway line.
There aren't a huge amount of activities in Tavistock, as it is a small town. The Wharf holds fairly regular music events and shows films- based near Plymouth Road. Meadowlands Swimming pool is based in the same area too.
Goosey Fair takes place every second Wednesday of October and takes over the town with fairground rides, stalls and various events.
The town's Pannier Market offers local goods and there is a weekly farmers market along with various other events offering local produce. Country Cheeses, located in the Pannier Market, is highly recommended for stocking up on local cheeses.
There are a number of small resturants and takeaways in Tavistock. A McDonalds was based on the outside of the town towards Plymouth, however, due to poor business this was closed down.
Pasties are for sale in various places and are arguably better than those in Cornwall, though don't say that within earshot of a Cornishman!
The Cornish Arms A friendly pub near the centre of the town.
Jack Chams A rather more trendy venue, located a few doors up the street from the Cornish. Bar upstairs, with a small dancefloor downstairs and a heated outdoor area.
Trout and Tipple A CAMRA award-winning pub on the outskirts of town, but with a nice local feel to it.
Various Bed and Breakfasts are situated along Plymouth Road.
The road to Princetown provides great Moorland scenery all the way and passes the Dartmoor Inn at Merrivale.
Morwellham Quay to the west is a most interesting living history site, though as of autumn 2009 it is in administration and temporarily closed. A number of villages listed under Dartmoor are within easy access.
Brentor is a small village near Tavistock with a picturesque church on the top of a hill.
Lydford Gorge is a 1.5 mile (2.4 km) long gorge near Tavistock. Owned and maintained by the National Trust.