Firstly, what are you thinking of buying? Do you mean a PRE (Pura Raza Espanola)? As there is no such breed in Spain as an Andalusian, that's just a horse that comes from Andalucia and to be honest there are some right horrors! The other typical 'Andalusians' are what they call a Tres Sangres (Arab/PRE/TB cross) or a Hispano-Arab (PRE/Arab).
I have never yet seen (but don't deny there must be some) a PRE that could jump to any height - they are bred to do Doma Vaquera and Alta Doma and have wonderful movements and paces. Personally I am not fond of the PREs but love the Hispano Arabs (they tend to be smaller and lighter).
This is all my own personal experience and opinion and I am in no way an expert on the breed.
If you're in Glos then you're not too far from here- http://www.dovecote-stables.co.uk/dcs/
If you're considering an iberian (and personally I prefer lusitanos) then you should get as much experience riding them as possible. These guys could probably help you buy one too (though quality doesn't come cheap)
Have you looked on the breed society's website? www.bapsh.co.uk
There are some nice UK bred PRE around (no, they don't have to be born in spain to be a PRE) and some are breeding awesome colours and good jumper types too!