Originally Posted by
WorldLux
That's somewhat bad advice depending on how much currency OP intended to change. The bureaux de change on and around Oxford Street charge as much as 10-15% on the market rate. Depending on how much the OP is changing, the OP might be better of looking for a shop with better exchange rates.
If they are only getting €50, then equates to an additional cost of between €5-7.5 which may be less than the cost of travelling to a bureaux de change further away