Hi ---
As the house was lived in by yourself up until 97 then it qualifies for CGT exemption as it was your PPR up until that date, there is also a further 3 year rule in which the house continues to qualify after the date you moved out, so that would take you to the anniversary date of vacating the property in the year 2000. Here (in 2000) is where the valuation will be taken into account and deducted from the final price you sell the property for, in working out the overall gain and the amount that is taxable. Then ............
Not only that, but having the main residence exemption available also means that you are entitled to a further exemption called "Private Letting Relief". This further relief applies to exempt up to £40,000 of the gain accruing during the period that the property was being let out as private residential accommodation.
Example house value year 2000 = £30k and you sell for £85k that eaquals a gain of £55k..... you can then deduct £40k Private letting relief = £15k taxable gain.
You are then allowed to deduct from this £15k... professional fees and major improvement costs incurred during the period and your personal individual CGT allowance for this current tax year £9200 (double if property was jointly owned). This for examples sake would mean you're liable for CGT on £5000 at 40% = £2000 tax due.(these figures are examples) less if you're a basic rate taxpayer.
You may find when you finally work out your gain that there is no CGT to pay on this transaction, depending mainly what the value was in the year 2000.
The above is just an illustration just replace all the figures with your own actual costs.
If you sell after April 08, I believe the CGT rate is going to be a fixed flat rate of 18% which could further save you money