I will present some results from ALMA observations of gravitationally-lensed sources found in the Herschel surveys in the redshift range 3 < z < 4. The huge far-infrared luminosities imply these galaxies are in the process of formation, and the resolution of ALMA combined with the magnification provided by the lensing allows us to study the ISM and the star formation in these objects with a resolution of only 50 pc. I will then describe the surveys at 1mm that we intend to start this winter with MUSCAT, a camera for the Large Millimetre Telescope that is being jointly built by the UK and Mexico. These surveys will allow us to push the study of dust-obscured galaxy formation out to 6 < z < 9. However, to make the best use of these new wide-field millimetre surveys, we will need complementary large-area optical surveys.