We are going to Spain on July. I basically hate spending extra above my basic contract on mobiles. My intention was just to stick phones on air plane mode and most probably just off while there.
However I did wonder if things had changed these days and maybe it doesn't cost a fortune to use it ???

still costs a fortune.

O2 charge £1.99 for 15mb of data usage.

Ok ta. I won't bother using it. Is Not really a necessity for me on hols anyway.

Costs in general have dropped.

So the odd text or short call isn't going to break the bank
But lots of calls and data usage is where it can really start costing a lot.

So yeh, wouldn't really use it unless you need to. Texts is cheap so I'd recommend that if you need to stay in contact.

It's pretty cheap but O2 have some of the worst roaming prices, although even then phone calls are 50p flat rate (the rest comes out of your minutes) and this includes international calls to other European countries. SMS being 7p to send, free to receive. Even if you send a hundred at that rate, the £7 charge would probably be minuscule compared to the overall cost of going your trip.

Yeah I'm more worried about all my apps that secretly connect using up roaming charges.
So if I just keep mobile data off I should be Ok.

Yeah, those apps can be a pain, even if you switch off sync, so you have to switch off data completely. That said, all networks have to cap your data charges now so you can't go over 40 euros or so without specifically opting in.

Be careful with this one as many networks have an automatic opt in just by you signing the contract.

Isn't this all going to change next year (or 2016 or something)?
I thought it was all going to change to the same prices as here then.
I know that doesn't help you now but just checking I got that right?

You are right the EU are trying to push it through at the moment main vote is in October/November.

Enjoy Catalonia.