Just to add my tuppence worth to Semi's comments:
The electricity supply can indeed at times seem a bit draconian compared to the UK. Power outages are still a fairly common event, especially during stormy weather. The power cutting off when you connect too many appliances at the same time, however, is more likely to do with the Kw supply contracted to your home. Some older homes may have a rather low supply. You can request to increase it from the electric company (and pay more for the standing charge accordingly). They will come out and change the power limiter in your fuse box - that's the one that's got a lead seal on it - or should have! Newer homes should have adequate supply for the typical range of appliances. 5.5Kw is about the most you're likely to need. I've never heard of builder's supply being 110v - surely their tools wouldn't work if that was the case? Some very old or rural homes may have 110v still, although it's pretty rare nowadays.
It is true that the water here tends to have a high calcium content which is a real washing machine wrecker. Use anti-cal pills in every wash (available from all supermarkets), but don't be too surprised if it's still knackered within a few years. Repairs are usually not economical, so maybe best just to buy a cheapy and change it every so often.
I'm no expert on TV matters; I know UK TV's used to need to be adapted in some way to function correctly over here, but I don't think that's the case any more. Not certain though. Don't know anything about microwave/mesh systems - never heard of it, and never seen it on CDS. If you live in a community, you should be able to connect via the community arial to digital terrestrial TV (Spanish) by buying your own decoder (available from around €40) and some programs can be switched to English language - but not many. Otherwise, you're looking at SKY. Again, if you're in a community with a lot of Brits, there may be a communal system in place, but more likely you'll need your own. This usually means a huge dish (1.3m diameter is best), a decoder, and if you want more than the free basic channels, a SKY card. There are many companies advertising their services, but be wary of any advertising "no UK address or bank account needed". These are basically resellers of SKY services, and you will pay a one off fee or an annual fee, but with no guarantee (from SKY) that you won't get cut off if this company disappears. I've heard that due to increased competition (Virgin) & pressure to stay within the bounds of the law (SKY has no licence to broadcast outside the UK), many of the thousands of cards registered to, for example, oil rigs in the North Sea, are coming under investigation! So IMHO, best to get the card yourself using a friend or relatives address in the UK, and bring it with you.
And if anybody wants to know how to get Channel 5, let me know.
As for clothing - bring it all. Yes, it really does get chilly in the winter! Marble floors are lovely, but boy are they cold when you've got no socks or slippers on in winter. And any clothes you find are surplus to requirement, the animal refuges will be very glad of, if not to sell on their market stalls to raise much needed funds, then as bedding for the many many poor homeless cats and dogs.