Take your time and be sensible - the survey is a normal backside covering with possibles, may need, in the future wording. Buying can be scary, especially for a FTB and reading surveys can initially look as though the house is about to fall down at any moment - it will not. It is however a period property which needs work doing sympathetically to it, but I think a lovely Cornish cottage which could be a lovely home.
Most of the money spent will be on the fabric of the house. Whilst this work is completed it is the time to also rewire/replumb purely because it is easier to do when walls/floors are likely to be having work done.
The areas in the survey which caught my eye is the concrete ground floor slab, interestingly the suggestion is to replace it with concrete again, I would possibly suggest using limecrete which will allow the house to breath.
Damp meters are useless as others have said produce readings which are incorrect and are used predominantly to justify selling damp proof courses which can do more damage.
As I stated at the beginning of this post, take your time, know how much you have to spend and research. Cornwall has a wealth of period property tradesman who I am sure can give their opinions and estimates for work and most importantly which work needs doing straight away.
Not everything has to be done at once, the joy of owning your own home is that everything does not have to be done at once. Living in a couple of rooms may be needed until you can finance other things being done.
The majority of property surveys, especially period property ones read as all doom and gloom, yet people purchase the houses. Head over heart, investigate the costs and timescales for the work to be done and go from there. As much as people are saying lower the offer to incorporate the work to be done, it doesn't work like that, the valuation has come back as it is worth its money. There may be some merit in attempting a small reduction in price but I think it is unlikely as many of the details of the survey are easily seen in the property, reductions only come when a survey shows something which was not readily visible.