Plug-in cooker hood?

[fircroftstar]

My hob is on a peninsular worktop with a low ceiling so there is no possibility of ducting to an external wall, therefore I need to install a 'freestanding' recirculating cooker hood.
My initial intention was to simply run the cable across the ceiling (in trunking?) to the wall, then plug in to the power outlet that is combined with the cooker switch (it would have to share duty with the microwave) - would this be ok?
There is a 3A fused switch in one corner that originally fed the old central heating gas boiler but is no longer used since the new boiler was relocated - would it be feasible to run the hood from this - it would involve more awkward cabling runs?

 

[ban-all-sheds]

Either would be "OK", as in safe and compliant with the regs, but flex across the ceiling, in trunking or not, is mighty tacky.

What's above the kitchen?

 

[sparkwright]

If no access above, and the joists run in your favour, you may be able to fish a cable across the ceiling.

Same goes for some 4 inch ducting to the outside, so you can have a REAL extractor.

If in doubt, a builder and an electrician may be able to do a decent, tidy job for you.

 

[fircroftstar]

The building is 18th C terrace, kitchen is a 'lean-to' single-storey addition to rear with no access to the roof void. The ceiling is lath-&-plaster construction, which I'm not keen to disturb more than necessary.
There is existing cladding (disguised as a beam) for the old central heating pipework from close to the fused switch up to ceiling level and along one wall that I might be able to dismantle and run the cable through - which is why I initially considered the simpler option of plugging into the cooker socket. In both cases there would only be about a metre of new cable trunking to the prospective hood location.
Cooking odours are more of a problem than grease and steam, so external venting is not so important.

 

[17thman]

If any of that plumbing in the ducting/false cladding is still in use, you need a 25mm spacing from cable to plumbing or a suitable barrier betweeen the 2