I think that Cat 1 is an 'approach and landing' category and therefore it is not relevant to take-off.
If your LVTO (RVR below 400m) are based on having certain aircraft equipment installed and serviceable (unlikely), then the MEL should restrict you to take-offs with RVR above 400m in the event of unserviceabilities.
If the MEL restricts the appraoch category to Cat 1, then the take-off is unaffected because there are no 'categories' for take-off.
If certain airport lighting installations are unserviceable, then the take-off minima may increase. This should be indicated on the Jepp/Navtech airport diagram. A generic table is here: (sorry for the bad formatting)
Facilities RVR/Visibility
Nil (Day only) 500 m
Runway edge lighting
and/or centreline marking 250/300 m
Runway edge and
centreline lighting 200/250 m
Runway edge and
centreline lighting and
multiple RVR information 150/200 m
Note 1: The higher values apply to Category D
aeroplanes.
Note 2: For night operations at least runway
edge and runway end lights are required.
Note 3: The reported RVR/Visibility value
representative of the initial part of the
take-off run can be replaced by pilot
assessment.
Note 4: The required RVR value must be
achieved for all of the relevant RVR
reporting points with the exception
given in Note 3 above.