recombining gas supplies where flats have been recombined into house

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Nearly a year ago we bought a house that was rented out to students. It had been converted back into a house and rented out a number of years previously. There were two sets of gas and electricity meters for the house. To simplify matters and reduce unnecessary standing charges I decided to recombine the gas and electricity supplies to the upstairs and downstairs so that they were measured by one meter each and there was one bill.

It was straightforward to do the electicity (electrician linked the two consumer units and took them off one meter. Electicity company removed redundant meter. Hurrah.

My question is about the gas. I would have thought it would also be easy: link the pipework to upstairs and downstairs so that it comes through one meter, cap off the pipe below the redundant meter and have it removed. HAS ANYONE DONE THIS? The gas fitter says he can do it but my hesitation is that SGN seem to keep saying that I need to have a full £800 ish disconnection rather than this capping off? With the electricity alteration the suppliers were originally saying a similar thing about £750 disconnection but it turned out we didn't need to. Is gas likely to be a different situation?

I don't want to pay the £150 the gas fitter has quoted for the job only to find that I have to pay £800 for a full 'disconnection' later.