I have a garage that id like to turn into a heated workshop...its single
brick thick with a tiled roof and no insulation. any products
recommended?

First you need to insulate. Don't worry about the single brick walls,
they're fine.

I'd recommend using 50mm of Celotex/Kingspan (not polystyrene!) solid
insulation on the walls. Then line with plywood, screwed to the walls
through the insulation into the brick. This gives something to hang stuff
off (and attach tall shelving/racking units to), and ensures no cold
bridging through studs or battens. Either paint or plasterboard the plywood.
I'd be inclined to plasterboard for fire safety.

The roof should also be insulated. You must ensure that there is sufficient
ventilation above the insulation. You can probably provide this using air
bricks or tile vents. The exact form of insulation will depend on what you
have. However, 100mm of Celotex/Kingspan would do here, lined with
plasterboard. Ensure there is vapour check on either the insulation or
plasterboard and that it is taped.

Now, a quick heat loss calculation (these may not be very accurate, as I'm
guessing u-Values a bit), assuming a single garage gives me:

Air Changes: 450W
Walls: 225W
Ceiling: 70W
Floor 585W
Access door: 155W (single PVC)
Garage door: 650W

As you can see, the floor and garage door are the real culprits here. You
will serious improve matters by loading the garage door with Celotex and
draft proofing it. You may need to adjust balance weights or springs to
allow for the extra weight.

The floor is less easy to solve. If you no longer wish to park the car in
there, then even 25mm of Jablite will drop the heating requirement
massively, although you need to decide what you need above, either lots of
concrete, or a suspended or floating wooden floor.

As for heating, if you aren't intending to heat constantly, then electric
heating should be fine. If the floor and garage door can be brought down to
reasonable values, then you are talking a peak loss of just under 2kW. A
2.5kW electric convector with fan boost, thermostat and timer would be
indicated. Alternatively, if the house central heating circuit passes nearby
and can be conveniently tapped into, then a 2.5kW radiator or fan convector
would be easily enough. If I didn't intend heating all the time, I would be
inclined to put a programmable room stat and zone valve in there. If the
system isn't suitable for subzoning, you can still install them, but they
would operate as a glorified timed TRV. As you are likely to want the timing
to be less than that of the house, this would not be too bad.

Christian.