Here are my restaurant recommendations.
This is a real British restaurant with good British food to try. It can be expensive, but try the children's menu (if you are allowed) for £4.95 or the theatre menu for £14.
It's on Henrietta Street, in Covent Garden - easy to find! But book in advance.
If you're missing Chinese food, try Wong Kei's. It is famous for having rude waiters and waitresses and many tourists visit there. It's also not too expensive (for London).
Wong Kei's is on Wardour Street.
This is probably the best place for fish and chips in Central London, but the prices can be expensive. Why not buy a portion to share for two people? Takeaway may be cheaper than eating in too. You can take your food away and eat it at Seven Dials nearby.
TR&SP is on Endell Street.