Hi Dicko,
I too have recently changed from town water to rain water and have noticed that my beers all went rather bland, with little malt flavour and little hop bite coming thru. I also noticed that I was getting very little break, neither hot or cold break material, and the levels of carbonation seemed a lot lower than they used to be.
I have since brewed one batch with additions to my mash and sparge water. I used promash to appoximate London water as I thought it was a middle of the road water profile.
I added
Gypsum 1.0g mash 2g sparge
Epsom 0.5g and 1 g
Baking Soda 1.3g and 2.75g
Calcium Chloride 0.5g and 1g
Chalk 1.0g and 2g
for 13 litre mash and 26 litre sparge.
I haven't noticed any funny smells but my levels of additions seem quite different to you.
Don't know if this helps at all!!
Cheers
Chris