Might be ok but how long is the cable run and how is it installed? I think 6mm is ok to 46A under perfect conditions. Perhaps half that if not. The 32A breaker may have been choosen to suit the derating required.

Is it a combined oven and hob or is the oven seperate? As the oven is <3kw it might be possible to plug it into a regular 13A socket. Many oven are now supplied with a plug rather than hard wired. That would drop the load on the 6mm to below 32A (7200/230) and then there is the diversity to help out.