Kitchen plinth cut to measure

B&Q sell high gloss white plinth in various lengths (its expensive ) and many of their stores (don't think all) do offer a free timber cutting service

They do have rules on what they cut and what they don't cut - for instance they don't cut treated timber due to the chemicals

Best to check if they cut high gloss material, it has a tendency to chip so they may avoid it

As for a cut out for a vent - they won't want to know about that !

Usually done with a jigsaw. If it's a flat vent that fixes to the face of the plinth you could always just drill some say 10mm holes through plinth to aid air flow

Other types of vent may well need an actual cut out, so ur gonna need a jigsaw ideally. Can you borrow one of a mate ?

 

You might get them to cut to length, but I doubt you will get them to cut a hole.

It's probably better to either employ a local handyman or buy a jigsaw and do it yourself

 

Mark the cut with a pencil line, stretch masking tape tight over the line, remark and square the line across plinth and cut with a sharp 10 teeth per inch handsaw. Peel tape off once cut is made, should be no chips or splinters.