Yes, you can walk it easily. Give yourself 10 minutes max, moving at a leisurely stroll. There is a covered walkway between the two to keep you dry in the event of rain.
It's worth asking the coach driver to let you out at T2 - they have to pass it by on the way to T1, so it's no problem.
If the coach stops in T1 in the same place as the various long term car park coaches, then you walk towards T1 (through the short term building). Once on the pavement on the far side of the road, head to your left. As I said, you'll have passed by T2 on the way there, so finding it won't be hard.