The table is 1190 x 470. I haven't dimensioned much up yet
So you have approx 1200mm long rails on the x axis? I feel they could do with some support really. I also noticed that the bearings are quite a bit lower than the table, could this be reduced to help with the gantry stiffness?

I guess with a design like this it will be a work in progress and you will tinker and tweak the parts as you make them, you'll soon get a feel for what works and what doesn't, allowing for adjustment is always a good idea.