Hi
Firstly if the modification/repair is not within 30cms/12 inches of a testable item ie steering, seatbelt mtgs, suspension etc then it should not be relevant to the MOT. If such repair/modification is within the 30cm area then the repair must be full welded with no gaps in the welding.
These standards only apply to load bearing areas and not to cosmetic items. Based on the above I would think it unlikely that your mods as described would fall within the prescribed areas as noted above. At worst it may be advised on @ time of test but unlikely to fail.
Allan