Take whatever will give you the easiest A!
There are no universities that specify further maths in their entry requirements. This is because many schools do not run that A-level. Further maths is good if you can take it because it'll help in engineering far more than biology (which probably won't help that much at all, to be honest, unless you're doing something like biomedical), but the relevant material will still be covered by the university. So you're not at a disadvantage having not done further maths, as long as you are prepared to work a little harder on the first year maths modules.
Now as you should be aware, A-level grades are paramount. So do not in any way jeopardize your chances of getting at least straight As. According the the latest UCAS figures, applications to engineering degrees have increased by 25% - most likely because people are really thinking of the career prospects and monetary value that their degree will bring them. So engineering degrees are becoming more and more competitive at the good institutions, which means that at least straight As will be the standard offer to applicants. Which means that if you get AAB with FM as one of your A-levels, you'll probably not get in, whereas AAA with biology instead will. With the best grades possible, you are a more competitive applicant to the best universities. And since the only value of A-levels are to get into university (they are worthless intellectually, trust me), you are better off picking the combination that is most likely to give you the best grades and make you the most competitive applicant.
Secondly, when it comes to graduate jobs, your A-levels are becoming more and more important. Many graduate schemes have a minimum A-level points tariff, which at the moment tends to be about the ABB-AAB level. But with grade inflation at both the college and university level, that's almost bound to increase. So play it safe and do whatever you think will give you at least AAA. In fact, I've heard anecdotally from recruiters in the software development field that they actually select their graduates based on their A-level grades rather than their university grades. Sounds silly, but you've got to play the game. With a chem eng degree you're probably looking at becoming an accountant, in which case your A-level grades are also extremely important.
So take whatever will give you the easiest A!