Orlando is probably most famous for its stunning theme parks; it is actually known as "The Theme Park Capital of the World", so you will definitely find all the fun you need right there. But the city is also nicknamed "The City Beautiful", so there is definitely a lot more to Orlando than just theme parks and fun.
Orlando is a great destination all year round, but the best time to visit it is between November and April, as this period is usually dry with cool temperatures below 30°C. May to September is rainy season with temperatures over 30°C, and June to October can bring some hurricanes. If you would like to see Orlando in its most lively edition, visit during the Mount Dora Arts Festival in February, where over 300 artists perform in Orlando's largest festival. There is also the Orlando Carnival in the last week of May with Mardi Gras parade, the Epcot International Food & Wine Festival, which takes place end September to mid November in the Walt Disney Resort, and of course the 4th of July - Independence Day, which is a national holiday in the USA with parades, concerts, fireworks and many other attractions.
Check if you are eligible for the US Visa Waiver Programme (VWP), which allows you to visit the USA for up to 90 days. Passports should be valid for the duration of your stay. The cost of living in Orlando is generally lower than in London, so eating out and buying alcohol will cost you less. Orlando is in the Eastern Time Zone, so it is 5 hours behind London (UCT/GMT -4).
When arriving at Orlando airport, you can easily find transfer to the city centre. You can take buses numbers 11 or 51; single tickets cost around $2. A taxi costs approximately $40. If you want to get around Orlando, you can find cheap public transport with several "Lynx" bus routes; single tickets are about $2, a one day travel card is around $4.50, and a 7-day travel card costs around $16. If you want to travel by taxi, then good news: taxis are cheaper than in London. If you are looking for accommodation, prices for 3 star hotels start at around $50 per night per person on average.