As far as school qualifications are concerned - 5 GCSEs and 2 A-levels (or equivalent) is about the minimum, though there are no hard and fast rules. A university degree in a related field can help you stand out from the pack, and it can also help as a backup plan if the flying doesn't work out - whatever the reason.
It is also highly recommended that you get a Class 1 Medical certificate before you start investing heavily in flying training - you want to make sure there are no underlying medical issues that will affect you before you spend all that money!
Lastly, and possibly most importantly - you will need support. The road to becoming an airline pilot is long, expensive and tough. Often the support of friends and family, emotional and even financial, can be the only thing left to keep you going through the low points - and there will be low points. With encouraging and supportive backing you can be ready for everything the journey will throw at you - it's not to be underestimated.
If you're looking to join a Pilot Cadet Scheme, be aware that they are incredibly competitive - our Cadet Assessment Preparation can help you get ahead.
There are two different classes of medical certificate for pilots: Class 1 and Class 2. A Class 1 medical is valid for 1 year (6 months if you're over 60), and allows you to fly commercially. A Class 2 medical is valid for 5 years (2 years if you're over 40) and is less rigorous, but is only suitable for private flying. An Aviation Medical Examiner (AME), of which there are many all over the UK and Europe, can issue initial Class 2 medicals and renew both types, but your first Class 1 medical must be done at the CAA's medical division at Gatwick at a cost of around £350 (their charges can be found here)
So, what medical should you get? If you are going down the modular route, then you only actually need a Class 1 medical once you start your CPL course (or ATPL theory with some providers) - you can get away with a Class 2 for all your PPL flying and hours building. However, it's generally a good idea to get a Class 1 medical before you spend lots of money on flying, just to make sure that you don't have an underlying condition that would prevent you from going all the way to CPL; also, if you let a Class 1 expire (and you're under 40) it downgrades to a Class 2 for a further 4 years, so you don't have to keep the initial medical current while you're doing the hours building, just renew it before you start your CPL.
We are happy to help if you have any questions.