For the record, engineering is a very maths (and physics)-based degree, and you can't study it at uni without doing both of these subjects at A Level (or equivalent). As for the sound of it, you don't enjoy maths an awful lot, so I would recommend you rethink this career plan. However, seeing as you've only been at sixth form for a couple of days, I would say that you should maybe give maths more of a chance. For an example, I found the core modules in maths slightly dull, but extremely enjoyed S1 and M1, the same way that I love physics.
Doing three sciences and maths is very tough in itself, and I would definitely not recommend you do this unless you enjoy all of those subjects, otherwise it'll make revision A LOT harder, therefore it'll be more difficult getting good grades. Like everyone else has said, drop the subject(s) you don't enjoy and keep the ones you do. You still have time to figure out what degree you want to do at university, and it'll become clearer the further you get into your A Levels and you begin to see what topics you enjoy more than others.
Good luck with everything!