I have just been through this whole process, got mine from Warrs HD in SE London at £180 odd so £120 is cheap IMHO, and the Spanish were concerned at first that it wasn't in Spanish! My fixer argued the toss for me, and it is VIN specific, that is what you are paying for. It had my VIN number on approved and says what tyres were fitted as standard etc. The difference was my X1 was never officially imported to Spain, only Germany and UK and a couple of other European countries.
Warning: make sure the silencer is within 4dB of the limit on the sticker on the frame, make sure all lights have an 'e' mark on them, and the headlight point the right way. They do question tail tidy stuff, but it won't fail the SVA test, at least in Spain it didn't, not sure for Portugal but probably the same.
Check out
http://www.ibexinsure.com for insurance, they cover UK plated stuff, in Gibraltar, Spain (and its islands) and Portugal. I use them and they are cheap and good service. They also give 60 days EU cover outside these territories! (all the brokers use them for expats)