Just to add my penny worth; I think 'Neon Boiler' is perhaps a reference to a fused spur used with a neon indicator that is supplying a water heater perhaps, do you have something like that? One of the tests carried out on wiring, is an insulation resistance test, part of which is live to neutral (sometimes referred to as 'live-live). A fused spur with a neon indicator, could affect the result of this test, if the spur could not be turned off, fixed behind a kitchen cupboard for example. The electrician may have recorded this on the certificate this way. I suspect the council have employed a company to carry out an electrical inspection of your property, prior to rewiring it. Some tenants carry out alterations to council properties, such as your kitchen. The council may have to decide whether to take on that responsibility when carrying out the rewire, for example your neighbour may not have extended or altered their kitchen, but you have. They may consider not to rewire the kitchen, if it has be properly done & carried out recently. If its not been done correctly, they may feel its your responsibility? As others have said, the reference to 'under floor wiring' is just that the electrician could not comment on any wiring without lifting flooring, it is a limitation on the inspection only, don't read anything into that. Normally, an 'electrical installation condition report', would be given to those requesting & paying for it. Sounds like someone, in error, has given you a copy. Could you provide a copy of your certificate here, the electricians here who carry out such inspections, may be able to explain the remarks for you?
