Who can carry out gas safety checks?

I think you could be right, Tinwheeler. After all, Gaslow and others advertise DIY kits for their exchange and refillable systems.

What JC says is correct in relation to buildings, residential caravans and the like but, unless regulations have changed in recent years, touring vans are not included.

Give Choose Leisure at Chartham (Canterbury) a ring .01227 733557 , got mine booked in there 

I stand corrected, my post wasn't totally correct. Sorry if I mislead.

Touring caravans and motorhomes that are privately owned and used are not covered by the GSIUR. 

Touring caravans and motorhomes that are hired out, are covered by the GSIUR

The short answer is ...Anybody!

I use a mobile engineer who at least has done a few courses with the appliance manufacturers.

Thanks for acknowledging that, John. 

We have addressed the OP's concerns in confirming caravan/MH technicians do not require Gas Safe registration for working on touring units.

I need to have my gas supply line refitted and also new hob added.  Any idea where I might find someone to do this west coast scotland?

Unless the regs have changed since the foregoing 7 year old discussion, any competent person can do the work. For example, a mobile technician, a caravan workshop/dealership, Bill next door, yourself…. The key is finding someone who knows what they’re doing.