You're not going to find a 13A plug on a non-induction electric hob. The existing hob will be hard-wired, and most likely on a 32A breaker and cabling already unless you have very old wiring or it's been installed by complete cowboys.
Having had a look now, this is the unit, seems hygena, no longer exist so probably quite old.
Is it likely to be some sort of dual unit or a stand alone job? I’m thinking it may be easier and better to replace the whole lot.
Power seems to go though this which does both appliances.
Any thoughts?
That cooker switch is pleasingly retro. I wouldn't be surprised if it predates the rest of the kitchen, especially with the inexplicable paint on it. Probably still safe but you might consider replacing it.
You're not going to find a 13A plug on a non-induction electric hob. The existing hob will be hard-wired, and most likely on a 32A breaker and cabling already unless you have very old wiring or it's been installed by complete cowboys.