You could try searching the Classic Camera Repair Forum for advice - though, if you wait here long enough, a number of its luminaries will probably offer advice*. And searching for Canonet should throw up plenty of threads.
If you can sort the lens - this may depend on the fungus, and the cleaning technique, as in both cases some are harmless and some make a terrible mess of your coating - the light seals should be fairly easy. Look for an ebay seller called Interslice - good kits, good price, good instructions.
Oh, and if you fancy a go youself, get some decent screwdrivers. A good jewellers set will probably suffice for most jobs, but JIS screwdrivers will fit most Japanese cameras better. There are few things more frustrating than getting stuck because one screw head has lunched...
* waiting is a good policy - get all the advice you can, see if someone else has done the same job before etc, rather than rushing in.