Been a few years since I could devote any real time to it, but I always went for Fox mainline, it was usually cheap for a big spool, and I never had any issues. I was fishing with 12lb or 15lb with my 2.5lb Carp rods with big Daiwa pit reels at the time. Learn how to set up a simple (semi fixed) ledger, hair rig, and a short string of boilies on PVA string. You could spend days learning/trying different rigs but that to me, is a solid base to start fishing for bigger carp.
A year or two ago I scaled down to 1.75lb test curve rods, small baitrunners and 6-8lb line which makes the better tench/bream a bit more fun while still having a hope of hanging on to something better (eg 14lb Mirror out of the canal last year). Since we just had a baby, I’ll be grateful just to get out with the match rod and float this year 😉