I did download it and these are my comments... bear in mind this is without seeing the installation.
Obs. 1 - "Main bonding conductor undersized for the property - C2" If the bonding conductor is 6mm and shows signs of thermal damage or is smaller than that, then I would class it as a C2, but if it's 6mm or above with no signs of thermal damage I would C3 meaning it could be improved but does not pose a danger.
Obs 2. - This is a little unclear "Socket in the garage on ring main has been spurred off for more than one point - C2". Having just seen the picture included in the report, yes it's non-compliant and warrants a C2
Obs 3. - "Connector blocks located within the DB - C2" - Unless there is clear evidence of thermal damage, this in my considered opinion is bunkum and does not warrant any kind of code. They are accessible for inspection and when the board is closed it's compliant.
Obs 4. - "Bathroom lights not IP rated for type of room. Require replacing as no extract fan - C2" Depending on where the lights are located they may require different IP ratings, and whilst not ideal it is entirely possible the lamps are compliant, for example, the zones end 2.25m above the finished floor level so above that the lamp could be anything you like. Having seen the picture, I stand by what I've said here... it looks like the ceiling falls outside the zones and as such the lights are compliant, not sensible, but compliant with the requirements of section 701 and as such warrant no code.
Obs. 10 - "Provision of additional protection for cables installed in walls containing metal parts - C3" - This usually refers to metal framed partition walls that are quite common nowadays or the kind of partition systems you find in offices, so unless there are metal framed wall(s) in the property this looks to be a bit of a stretch. If it's the fact we put metal in the walls, then that should be earthed anyway and doesn't fall under the remit of this (IMHO).
Obs. 12 - "Additional protection by rcd... blah blah blah... for circuits passing through zones 1 and 2 and not serving a location containing.. blah blah blah - C3". Unless there are cables under the bath (i.e. above the floor and below the bath), then I think this is unlikely because the walls, the ceiling and the floor constitute an end of the zone at the most basic level. Cables running in them are not 'in the zones'. As such, this shouldn't be on there in my opinion.
The rest seem fair, but of course that's without seeing the installation.
Looking at the test results, I'd question the insulation resistance results for 7,8,9,10, looks like they've tested them as a block. I'd also question the r1, rn and r2 results for 9 and 10 as they are identical whilst other results are quite different.
The comment about the whole installation having an IR less than 1Mohm, that is most likely down to circuits 2 and 5 as they have very low readings, so much so that if I were testing, I'd probably have disconnected them or at least made some attempt to try and find why they are so low, particularly circuit 2 which appears to show a dead short for all the tests (worth looking at during the inspection in my opinion because that could present a real danger).
As for the statement that alterations could overload it, I think that unlikely given most of the socket circuits are 32A a piece.
As has already been said, there is little evidence in the report to support making the statement 'it needs a rewire' but, as you're going to want to make changes it's a good time to do it before you've decorated and put your stamp on the place.