What I would intend to do then is;
New cooker control box 45 amp, 2 cables from it
1. 6mm to cooker outlet for hob.
2. 2.5mm to fcu (switched) for oven (MI says minimum 13 amp fuse)
6mm cable to run vertically to below worktop level then horizontally to outlet.
2.5mm to run vertically into back...