Topman has revamped its personal shopping lounge at the flagship store at London's Oxford Street. GQ have much more info so read the Topman article here.
Anyone can book an appointment up to 6 weeks in advance with no obligation to buy. They'll even select some items for you in advance if there's a specific event you're dressing for. I've met the personal shopping team before at Topman and have to say they are extremely knowledgeable and have so much experience. You'll be in good hands.