Accounting for renovation expenses

[mknight]

Hi,
Several years ago I bought (as an investment) a commercial property. It required substantial renovation which, in total, cost the same again as the purchase price.

Some of the work was done by a main contractor and I have 'proper' invoices and completion statement. However, a large amount of the renovation was project managed (as a novice) by myself. Much of the receipts, therefore, are directly from suppliers (trade and diy stores) and self-employed tradesmen.

The result of all the work is a current market value in excess of what I spent and, as such, I assume there will be CGT upon disposal.

I intend to keep the property for quite a while. What I'm wondering is how do I make sure that I can properly account (if required to do so) to the authorities the renovation expenses incurred? There are a huge amount of tiny receipts and I'm concerned that with time many of these will fade (thermal printing).

Is there any method by which I can properly document/account for the capital expenditure? (Maintenance etc since property has been rented is accounted for in self-assessment)

Also, am I correct in assuming CGT is applicable and not Income Tax? The property was redeveloped (commercial use with flats above) but was bought as an investment.

With thanks in advance for any assistance.