If you think the timing belt needs to be replaced, then do it. That's not something you toy with. Your problem with the smoke however sounds like either you have a bad valve seal or maybe one set of rings is going bad. Pull your plugs and do a compression test or have it done for you. If there's a major difference in one cylinder, then that's your problem. Take the cap off a quart of oil, fill it, then dump it in the cylinder and redo the compression test on that cylinder. Assuming that the compression wasn't HORRIBLY different, then this will tell you if it's the rings or the valve seal. If it's the rings, then the compression will go up. If it's the seal, it won't. The valve seals aren't THAT difficult to replace for a D.I.Y mechanic with a set of wrenches, sockets, and a pry bar. You just have to be careful and make sure that you turn the piston under the valve you're working on to top dead center before you take off the valve keeper or you'll need to pull your head to rescue your valve.
It's not broke... It's just.... Ok it's broke but I can fix it! Where's my duck tape?