Hi Barrie and welcome to the forum.
Having an EU passport is great, because you can move to Spain as an EU citizen and apply to join the register of foreigners when you've been here 3 months. Are you moving on your own, or will family be joining you? If the latter, do they also have Irish passports, or UK? If the latter, they will need to apply for residency as family members of an EU citizen. Let me know and I can post the relevant links.
A couple of other things for your own registration application, as an EU citizen you will need to show income or savings of around €7,500. Property ownership in Spain, especially without a mortgage, will also help your application. If you're not initially working and making social security contributions, you will need private health insurance.
It's worth noting, for the purposes of timing the sale of your UK property, that the Spanish tax year runs from 1 January to 31 December and you become tax resident in Spain once you've been here for 183 days (6 months and 1 day). Tax documentation is submitted a year in arrears when you will be required to submit an initial Modelo 720 Declaration of (worldwide) Assets (between January and March) and the annual Modelo 100 Income Tax return (between April and June). If you do decide to make the permanent move, you should aim to sell your UK property before you move here and ensure that you spend less than 183 days in Spain in the same year. For example, sell your UK property during the first half of 2025 and move to Spain in the second half of that year but less than 183 days in country, ensuring that you don't become tax resident until 2026. If you make yourself tax resident in the same year that you sell your UK property, you will potentially be liable for payment of Capital Gains Tax in Spain.
A couple of general points: don't pay any money to an estate agent (especially for the so-called "reservation deposit"). The legally binding deposit of 10% of the purchase price should be paid to your independent lawyer, not one tied to the selling agent.
I've entered your search criteria in Spain's primary property portals, Kyero and Idealista, to give you an idea of property types in your budget:
Kind regards,
Kim