You will need a Bb trumpet or cornet to start trumpet lessons. In my opinion the best brand new beginner trumpet is the Yamaha 2330. Though these instruments cost about £350 they play almost as well as some other trumpets that cost £1000+ and come with th aproval of most trumpet teachers. You could do your grade 8 on one of these but you would probably want to upgrade to a better trumpet at about grade 6 standard. The Yamaha 2330 comes in either laquer or silverplate. The silverplate is slighty more expensive than the laquer but it can offer more durabilty and can help to add brightness to the sound. Having said that some people prefer laquered instruments. On More of a budget I quite like the Bach 100T which costs about £150. This is a decent trumpet which made and designed by the most famous trumpet maker. This trumpet would quite happily take you to garde 5 and beyond but you would probably want to upgrade at this point. For a step up instrument I would look at the intermediate yamaha models 4335 and 5335 or, in particular, the Schagerl 610L or 620L which are amazing value for money.