If your circumstances are such that you will become resident in France or Spain then the tax consequences are different. What follows is a very brief outline of some of the rules. There is no substitute for local professional advice.
If you are non-UK resident, any rental income arising from property overseas is generally not taxable in the UK.
If you cease to be resident in the UK but actually stay out of the country for less than five complete tax years you can remain chargeable to CGT. This could mean that any gain made on the disposal of an overseas property would be potentially chargeable to UK CGT. Your IHT position will, as stated above, depend on your domicile rather than residence position.
If you become resident in France you will be taxable there on your worldwide income and gains, subject to the double tax provisions.
The annual wealth tax is charged on a worldwide basis for French residents. The French equivalent of council tax would also be due.
French IHT would continue to be charged on French assets only, unless you became domiciled there.
If you became resident in Spain you would be taxable there on your worldwide income and gains subject once again to double tax provisions. The annual wealth tax would also be applied to worldwide assets.
Spanish Inheritance and Gifts Tax applies as described above.