Hey mate, I'd probably first check for continuity (with a multimeter) of the low tension lead (small wire) from the distributor side of coil to distributor and also check low tension continuity through distributor when the points are closed. If the points are closed you should get a reading from dist. side of coil to any earth on the car/block. If that's fine, it may be the condenser. If you don't have a spare one lying around to quickly replace, you can diagnose it by checking for a spark jumping across the points if you manually open them with ignition on. To do this, disconnect condenser and make sure the points are closed (follower on back of cam lobe). You may have to roll the car a little in top gear to turn the distributor to where you want it. Then turn ignition on (to power up coil), and separate points manually by prying apart with a small screwdriver. If all is well, you should see a small spark jump across the points. If spark is good here, I would limit the number of times you repeat exercise as the spark without condenser will not do your points any good. It will be fine to do a few times though. If the condenser is faulty you probably won't get any spark here, or at best you might see a very small weak spark.

Good luck!