I'm sure you've had a few replies by now but here goes. the condition to which you refer re your mortgage is primarily an issue of the garantee which a registered specialist can provide, ie they kinda have you by the nuts. Best solution is if you don't need to borrow the whole amount of the value of your property that way it's nothing to do with your loan to value. Some argue that if you don't get the garantee then when you come to sell you snookered-not necessarily so since by the time you come to sell you won't have excessive moisture readings-if you do it correctly. Re you floor, if it's really wet in there, there might be timber issues. Beware the chemicals which tell you to be out the house for 48hrs, many are linked to trials in the states re MS(not Marks&Spencer!) Remove the top 30mm of your solum(the floor-messy)obtain a product called Visquene(spelling-fancy polythene stuff) from your Building Supplier, lay it on the solum making sure it comes up around 60mm higher than base of walls-including any dwarf walls(the inbetween ones down there)Lay a layer of some form of balast material onto this which will maitain the position of the membrane. Some folk put a concrete layer on top of this, not all. As for the walls, they may need whats called Injection DPC(Damp Proof Course)This is really a hit or miss proceedure(thus the mortgage garuntee thingy) and means drilling holes, generally at skirting level and squirting silicone based gunk under pressure into the holes-the idea being it will create(as if by magic)and impermiable barrier to moisture. You can hire the stuff to do it from HSS etc. You will not have a garuntee for this work remember. Dont put wallpaper on your walls downstairs for at least a year, just emulsion which will breathe. Make sure no flower beds etc are higher than level of DPC ie your house is wet for a reason. Clean all underfloor vents to allow air to circulate in there. I then, whilst I had the floors up stapled a kinda basket work of string under the joists and hung loft insulation between the boards for greater insulation. All depends on levels of moisture etc by the way. Timber specialists will generally give you a free quote as to exactly what needs done but be aware many of them are bloody crooks. Enjoy
Stuart
