If you continue to live in the UK, you are unlikely to alter your basic position of being resident (and ordinarily resident) here. There is nothing that would allow the Inland Revenue to view you as becoming non-resident. Similarly, if you have a UK domicile (ie this is your ‘permanent home’) that too would continue.
If your UK property is sold and the move abroad takes on a permanent hue, then the Inland Revenue will probably accept that you have become not resident (and not ordinarily resident) for UK tax purposes. Domicile remains difficult to change and you will need to demonstrate a fundamental change in your lifestyle and an intention to make the overseas country your home on an indefinite basis. In any case you will remain domiciled in the UK for inheritance tax (IHT) purposes for up to three tax years after your departure.
It will be situations in between these two extremes where there could be issues. If you spend an increasing amount of time in your overseas property, you may be able to establish non-UK resident status provided your visits back here do not exceed 91 days a year on average. This may require careful management of time and should be carefully documented so that any arguments can be supported. You may also be able to claim not ordinarily resident status but you will be unlikely to be able to argue that you have shed a UK domicile.
A person who lives in France or has their principal abode in France (assuming another home elsewhere) will usually be treated as resident in France. This would certainly be the case if you spent more than six months in the country. A period of less than six months might be sufficient if the time spent in France was greater than the time spent in any other country.
If you intend to work or run a business in France it is important to note that residency can also be established by performing the principal professional activity in France or by France being the centre of economic interests.
The starting point for Spanish tax residency is spending 183 days in Spain in a calendar year. Temporary absences will not reduce the 183 day rule unless you can show that you are still resident in the UK.
The Spanish Tax Agency may use the place of principal economic interest or professional activity as indicators of residence.They are also able to consider the location of a permanent home in Spain if the family live there on an habitual basis.