In the UK you can almost buy any car second hand with that amount of money. I have seen so many UK cars being sold at only a third of the price they would get sold for in the rest of Europe
2003 is a RAV4 mark 2. Good car where the 4WD is not that much more expensive then the 2WD, but only at servicing.
Manual RAV4 have issues with 5th gear at the mark 1 version, but as far as i know that was resolved with the mark 2.
Always check for the CEL (Check Engine Light) to come on after you turn the ignition key for a short while. If it stays on: bad sign, if it doesn't come on: move along, that car has been tampered with and bad things might be hidden there.
Check the profile of the tyres, if those look out of balance, high costs will come to you, so better move along then too.
See if the timing belt has been replaced (should be around 100K miles/ 160K kilometers) and if that included the waterpump (is highly recommended to be done at the same time, waterpump otherwise will go shortly after and needs belt to be taken off again).
I cannot give much more specifics about the diesel since i haven't owned a diesel RAV4 myself.
But the RAV4 are very reliable cars which can do many many many miles without major problems if well maintained.