Hydrogen is in the latter testing stage and is being trailled on a few new housing estates but it only takes a couple of parts within these boilesr to convert to NG.
Follow ExSurveyors advice re finding somebody, preferably from personal recommendations and not a trusted website who may be able to repair it.
If you do have a new boiler then depending on what condition the radiators are in upgrading to type 22 from type 21 with TRV`s can also make a big difference and save heating costs in the long term and nobody can advise on the pipework from their armchair Im afraid so you need somebody on site that you feel you can trust to advise you.