Hi. My name is*****'m looking at your question now and will post my answer or ask for more information here in a short while.
Take a look here for information on pre-letting expenditure.
You can claim for some expenditure in advance of letting a property for the first time but not large scale capital expenditure which enhances the value of the property. So, costs incurred to make the property fit to let (repairs and maintenance) would normally be deductible. I don't think ground rent and council tax are incurred wholly and exclusively for the purposes of the letting as you would have had to pay them in any event so I would not claim them. The same applies to mortgage interest in my opinion.
I hope this helps but let me know if you have any further questions.