I'm starting my 4th year this year. At my university, they retaught the AS maths syllabus in the first year and then taught more advanced calculus in the second year. Don't worry too much about the mathematics. It'll help if you freshen up, but essentially, because everyone was taught different things depending on the Country they took their exams or the exam boards, they basically reteach everything you need so that everyone is on a level playing field.
If your course is common (i.e first two years are same for all engineers), then you'll learn thermodynamics, fluid dynamics and mathematics. You'll probably do some electrical type course too and some control. You'll also be doing plenty of CAD and programming, typically C/C++. It sounds daunting but its taught well. After the common years you get taught flight mechanics / dynamics, flight control and aerodynamics.
If your course isn't common, you'll basically still learn more or less the same things, but everything is based on aircraft. You'll probably start aerodynamics a bit earlier too.
All engineers will have a variety of team projects, sometimes with one or two friends, and other times in larger groups. Occasionally the projects will involve other engineering students from different disciplines.
You might get lucky and have a bit of practical work - you probably will, but the majority of work will be theoretical.
You'll have plenty of tests throughout the year that count for a small amount. You'll have several exams for each unit, sometimes its split between Jan and July, other times not, depending on your university. The exams aren't tough if you work throughout the year, but trust me, you DO need to revise. Revising the night before and you won't get a first. I guarantee that. Usually, the exams are of a reasonable level and if you do past papers and revise thoroughly, you can definitely get a 2.1 and maybe a first if you do know your stuff well and are able to do the problems. Most questions are maths based problem solving questions. They should give you example sheets to help you and past papers. Make sure you do the example sheets (the practice questions) otherwise more than likely you'll fail your exams. Many people do the example sheets as part of their revision which is a decent idea. The other questions will be explaining principles and demonstrating knowledge.
Make sure you work in first year. Some universities, the first year doesn't count for anything towards your final degree mark. But the first year teaches you the foundations in everything. If you understand and remember the foundations, EVERYTHING becomes a lot easier, particularly when having to read things with textbooks in later years. I can't stress that enough- work hard from first year and do not take it easy. Engineering is a very difficult degree. You can take great pride doing well, but you do need to make sacrifices. You can easily have a social life / freshers week / societies, but make sure you stay ahead of your work. Even if you can't stay ahead, stay cool and keep working. Most people always have work to do in engineering. My favourite saying is, "If you don't have anything to do as an engineering student, you are probably doing something wrong".
Finally, it sounds daunting, but it gets better as you go along and start learning really amazing things- and start understanding the world around you.