Madrid/Cuatro Vientos airport has no precision approach procedure on site, so you would need to fly away to shoot these approaches. There are, however, several such airports nearby (Madrid/Barajas might be an option at quiet times, otherwise Madrid/Torrejon AB, etc).
The standard of their IR should be the same as in the UK since they are a JAA-approved FTO. Just make sure that your instructors are either very proficient English-speakers or British/Irish etc. natives.
2-3 weeks for an ME/IR? No way! Even with the world's best flying weather, I don't buy it. The MEP rating itself would typically take about 6 days to a week, which would leave you only 2 weeks or so for the IR... Yeah right! A 50-hour, JAA, Multi-Engine Instrument Rating course in 2 weeks?
As has been mentioned, the best thing to do is ALWAYS to visit the FTO and ask the relevant questions before commiting the sort of money we are talking about (around £9,500 at Aerofan if I recall).
Cheers
