When planning your trip in UK you should consider:
Bus or train
Long distance journeys in many countries are delivered by railway transport. When it comes to Great Britain, the price of the train ticket depends on the remaining time until the departure date and the number of bookings so most of the time you have to dig deep in your pocket. Megabus is, in my opinion (unbiased as they are not paying me), a good alternative for long travels (from England to Scotland or to Paris). Their buses / coaches are running on a regular basis to Scotland’s furthest regions. Bear in mind that sometimes you will have to switch to another vehicle of the same company on your trip. One advantage is that you will admire the countryside and the greenery along the way. You won’t be able to enjoy it from the plane, will you? Remember, check out in advance their website for fares and destinations: http://uk.megabus.com/
London’s transport system is one of the oldest in the world. You can write a whole book about the topic.
If you stay for more than just a couple of days it is recommended that you buy an Oyster Card. It is the thing that distinguishes the Londoners from the confused tourists. The locals use it on buses, the tube or the national rail. Whenever you want to enter or exit the underground just use the yellow card readers. The whole city is covered by several tube lines. Make sure to take the free map planner leaflet, found on each underground station. Besides, if you are wondering what to do with the card when back home, you may give it to someone either as a present or for his future journey to London.
Always check in advance the timetable. Especially, if you are planning an airport transfer or are about to attend an important meeting. During the weekends the running lines tend to be reduced so look for alternative routes.
Pitfalls on the road
Just to let you know. In the capital there are certain times where you would be stopped on a bus station prior to the final one. Make sure to enquire another ticket in case you have to transfer to another bus.
Weather conditions are likely to cause disruptions for all kinds of transport so it is crucial for you to have up to date information in order to avoid unpleasant surprises.