Wall mounted Xpelair 6" or Vent-Axia 6" (150mm) with pullcord or
remote switch.

The remote switch versions COULD be very useful.
You could use it with a runback timer such as the Electrisaver
15/30/60min or 30/60/120min, so set it when starting cooking, it runs
on after cooking to get smells/steam/heat out, then shuts off
automatically. TLC do a cheaper runback timer for about £15 with blue
LED if it suits your environment (Electrisaver is discrete red).

You can get runback timer fans GXC6T is one, about £69-92 from www.dealelec.com
amongst others (sometimes on Ebay really cheap, like £20 new although
not often).

Aside - the Electrisaver timer could also be used with a cooker hood,
providing the same and very useful functionality. A simple prod for
15min runtime for breakfast, or 60min runtime for main meal with a
"push it back up to 60min and leave the oven door wide open to get the
heat out of the kitchen" just after you serve the meal.

You need appropriate fusing & isolator.