You can’t turn into something else, no.
Solid results across the board. 
(Both OLevels and ALevels will be used).
So your total budget is 25k - about 6k per year – working on campus can’t be used to pay for room/board, just your miscellaneous expenses like toothpaste or new socks or a pizza. Typically you’d earn $350-400 a month through hours done on campus, which is very very little due to cost of living. Textbooks alone could cost $400-500 - although you can make copies at the library or use the reserve to lower costs, you may have to buy a clicker for a class, an online workbook…
To give you an idea, socks would be $10 for a basic pack, pizza about $20.
(Before you get a visa you’ll have to show evidence your parents or family have a plan for 4 years. That plan can’t involve working off campus to make money.)
So, if you can afford 6k, you need almost a full ride and is very very hard to get.
Do you have family in the US that’d welcome you and let you stay for free while you commute to a university?
Try to get the highest possible score because that’d open merit scholarships at public universities.
Then you have meet-need colleges but many don’t offer Engineering so competition for Engineering is crazy.