London in the summer

Planning a trip to London in August-end. any suggestions on places to stay at, eat, visit, party, or any other must-do things

Any ideas for day trips in and around London. Can I do Scotland & Ireland with UK Visitor Visa

Where to shop (if my budget permits) and what..

Also, how much Forex to carry, card-cash split.

Is the weather gonna be bad? Any suggestions on what to do or carry (umbrella perhaps?!)

Suggestions and recommendations are welcome :)