gcses don't affect you that much in terms of uni courses, they'll just want at least a 7 or 8 in maths and science. do triple of that's offered as a separate option, as for a level you will need to do physics for engineering, so this will give you a bit of a head start. CS will also improve your maths skills, so if you want to take that, go ahead, you could even take it for a level, as unis will respect it.
in general:
unis will definitely want physics (so do triple and try to get at least a 7)
also try to do well in maths, as they will also want maths a level
(not relevant to gcse, just extra info) depending on the type of engineering you want to do your other science grades will be important too (e.g. for chemical engineering, unis will want maths/Phys/chem or maths/further maths/chem, for mechanical engineering, unis won't want chem but they'll be impressed with CS, which you can do at a level without CS gcse, but obvs it is easier to do for a level if done for gcse)
what I'm trying to say here, is do what you enjoy as if you pick subjects you enjoy, you will be less stressed and therefore perform better in the core subjects needed for engineering (maths, sciences). if you're really keen, pick CS to experience it and see if you want to do it as an a level - but as I said, you don't need the gcse to do it as an a level.
Also tech is good too - you'll be able to see if you like engineering.
I know this is really long haha, but honestly don't stress, pick whatever you like! you'll be fine x