They will be 45 Euros in Spain for 200. Prices there are regulated so same price everywhere except airport where they always seem to be more expensive.
Agree they will be 45 euros in tabacs for 200 and nearer 50 at the airport. Only disadvantage with getting them in shops rather than airport is you have to have room and weight availability in your case. Give her £50 and sort out any discrepancy once she returns.
And just for completeness your friend will be committing an offence by buying and bringing back to the UK cigarettes which are not for his/her personal use.
Assuming 20 to an individual pack, a box of 20 would be 400, which at £60 would be 15p each. Heck, a pint of beer is often more than 26 times that ! Cheap as chips, and no incentive neither to start, nor to give up.
Not everyone does it. I don't for one (and there must be others). I don't do it for two reasons: (1) it is an offence and (2)I would not help or encourage anybody to smoke. But I accept that many people do it. I also agree that the chances of being caught doing so are as close to zero as can be imagined (certainly where such small quantities are involved). But all I was pointing out is that it is, nonetheless, an offence to sell dutiable items which you bring in from abroad.