Gas leak in kitchen

Typically if the suspected leak is in an inaccessible location, the pipework would usually be capped off on the incoming side of that inaccessible location and new pipework laid using a different route. It is often easier and cheaper to run pipework around the outside of the house in these circumstances. Eg when dealing with concrete floors, wooden flooring, floor tiles etc. It is possible to lay gas pipelines into concrete, but there are several regulations that have to be followed when doing so which will increase the cost compared with easier routing. Either way you will need to consult a Gas Safe engineer who will visit the site and better advise you

Find easier route for a new gas pipeline, it’s the cheapest way!

And again finding the easiest and cheapest route to the appliance.