You should certainly be able to get by on £200 - you could get by on £200 a day including paying for accommodation if you stayed in *really* basic places. When I spent a month travelling round in the States I saved lots of money by buying food in supermarkets, and eating main meals at lunchtime rather in the evening to take advantage of special offers. Have you been to London before? I can recommend lots of free/cheap places to visit if you are interested.

I saw JB on tour in October - he was amazing and I had a fantastic evening.