CGT on eventual sale of converted derelict farm buildings

We have lived for just over 25 years in a once derelict farmhouse, outbuildings and grounds (footprint 5 acres). We wish to sell and downsize and are worried about liability for CGT. The property consists of the farmouse - our principal residence over those years - an attached cottage converted from a former hayloft and a separate detached cottage which was once a cowshed. We incurred the purchase price and then the subsequent renovation costs to make the buildings habitable. On completion of the renovation, we eventually allowed the attached and detached annexes to be used for holiday letting and they are still so used. To bring them from dereliction to their present high standard obviously cost tens of thousands of pounds. Will we be allowed to offset these substantial renovation costs against any liability for the cottages? The farmhouse is our principal (and only) private residence. The two holiday cottages - and the associated business - are now owned and run by our daughter who does not live on site. Part of the cost of renovation and improvement was for our daughter to create a separate garden area for each cottage, all within the overall site. We would much appreciate HMRC and fellow forum-users' advice as conscientious tax-payers and yet wishing to take advantage of any legitimate mitigation.

Hi,
Full private residence relief is available for the farmhouse and it's grounds up to the the permitted area of 0.5 hectare. Please see the guidance at
CG64350P for full details.  
CG64350 - Private residence relief: garden and grounds
With reference to the annexes, any private residence relief due on the disposal of these will depend on the circumstances of the case. If these cottages were considered to be part of the main residence and grounds originally, some relief may be due for the period up to the date they were separated and used as furnished holiday lettings.  
When considering the renovation costs for each of the cottages, some of these may be deductible as capital expenditure when the assets were transferred to the daughter. See CG15180. CG15180 - Expenditure: enhancement expenditure
Note that if the expenditure took place before the holiday cottages were transferred to the daughter, this expenditure can only be claimed on any capital gain arising from this transfer. The enhanced value will already be reflected in the higher market value at the time of transfer and so no further relief will be due if the daughter later sells the properties.
Thank you.