I was wondering if somebody has done something similar with just an op-amp? I know it would be possible however since I have to amplify 100-300 times I'm getting probably a lot of noise. Would that still work? Any suggestions or past experience is greatly appricieated.

The voltage from a thermocouple is so small that an instrumentation amplifier is usually required.

How good an amplifier you need is depending on the precision required. If your application can accept an error of, say, 25 degrees, then go the cheapest solution where the max amount of noise and drift does not exceed the equivalent.

If you need very precise, you may have to resort to a chopper stabilized instrumentation amplifier.

If you need truly low noise DO find an appnote (AD/Maxim or an op-amp book) on the 3 amplifier TRULY differential input circuit. If I had one handy, I would, of course show it, unfortunately I do not, but there are plenty appnotes (try a search on 'bridge')

Erik