Is the above going to be possible? I have had conflicting information about whether it would fit & enable to the top drawer to open. I would like a 5 burner induction hob - if anyone has suggestions for models of hob. Or a wide 4 burner. Thanks
For all practical purposes, the answer to your question is no. I don't know of any hob that would allow you to open the top draw using a 20mm worktop. If your top draw runners don't foul the draw underneath it, you could lower the runners by 10mm and then raise the draw front by 10mm. If that isn't an option, then the top draw front would have to be fixed as a dummy draw front.
Just an afterthought. If the draws under the hob are 600mm wide, you could use a drawbox that would normally be at the bottom of a built under oven housing and then fit your 600mm top draw front to it. Built under oven housing draw boxes are only about 50mm tall and would allow enough clearance for the hob.
In that case, if you give DIY Kitchens a call they almost certainly will supply a 900mm reduced height drawbox using built under oven housing runners and draw box sides. All you then have to do is fit the 900mm top draw front to it.