Stroll over to the popular nearby St. Stephens Tavern where they are offering a great deal on fish & chips today.
This might be a good time for me to mention that in going over your funds, I found you're running low, but I have a solution. After lunch (before jumping on the Tube that is conveniently located at St. Stephens) take a few minutes to busk for some extra money. Should you not know what busking is, consult that English>English dictionary I mentioned previously, or watch the video below!
For example, if you make £5 per song and sing 7 songs each lasting about 2 minutes, you'll end up earning £35. Not bad for about 30 minutes of work, including breaks between songs!