M&S Money Exchange. If you prefer to use your own mobile phone, the number you need to dial can be found on the cashier's window. Select from the list which store you wish to collect the currency from.
M&s travel money services offer not only euro but many other currencies at competitive rates. Be informed and get ahead with. Buy more for a better online rate.
If you're planning a trip abroad you can buy your holiday currency and your travel insurance from m&s bank.