My phone is locked to Vodafone, bought in Spain. If I got a Vodafone UK sim card would it still work in it?

No.

Ring Vodafone and they will send you an unlock code - costs about 25 euros.

25 euros, bloody hell at that price I think I will keep my old Nokia block for my UK visits.

thats what I have done.
I have an old Nokia 3310 basic phone for the UK, logged on to the Vodaphone website so I can top up online with an old original low cost PAYGO tarrif

~

Yes, it just seems a shame that I now have a spare smart phone.

If you originally had a vodafone contract, and it has completed its minimum term, then your vodafone shop should unlock it for you. They unlocked mine, for no cost, and the nice lady even cut down my Asda sim for me.

I might give that a go, been trying to get Vodafone UK to unlock my two previous smart phones they originally supplied for over two months, the latest sin I have made according to there customer services is asking for 2 phones to be unlocked at the same time so they have put a block on the request again
Haven't thought about taking it into a Vodafone shop

If you look on ebay you can get phones unlocked for under £3 you just need phone model and imie number it tells you how you get that also it should be printed under the battery, which you send off as part of the order and you get unlock code sent by email within 24 hours. I did one that way last week it worked perfect. Some phones can be unlocked free I did a couple to bring to Spain other week from the giffgaff site, but they only work for certain phones.

Mine just told me to phone and couldn´t be bothered. And yes I did have a Vodafone contract.