|>>|| No. 2347
For comparison, a normal 60 watt bulb puts out 800 lumens and a 100 watt bulb puts out 1600 lumens. That would be a reasonable range for adequate lighting of a single garage.
Your choice will depend on how much battery life you need. If you'll only be in there for a few hours at a time, I'd suggest a rechargeable work light. This will give you a broad area of bright light, like an outdoor security light. The one at the link below will run for three hours on a charge at a maximum brightness of 1400 lumens. If you'll be in there a lot, I'd suggest adding a leisure battery, which will give you much longer running times. For working on the car, I'd also suggest a headlamp, which will give you good lighting in awkward corners.
For heating, you've got a choice between propane and paraffin. A propane heater is generally a bit cheaper to buy and heats up faster, but you have the inconvenience of taking your gas cylinder to be refilled. A paraffin heater can be a bit smelly and you occasionally have to fiddle about with mantles and wicks, but it's less faff to refuel. In either case, you'll want to make sure that your garage is very well ventilated and I'd suggest a carbon monoxide alarm.