Maybe you could speak to an adviser at your local college and they could discuss the various options with you and then see what might be best and what you need to achieve to do each thing.
I have just completed a b tech level 2 in animal care at 29 (just turned 30) and on track to pass with distinction so the colleges advise for me was to go on and do the b tech level 3 in September as I want to go straight in to employment after that and doing the higher level qualification will boost my career prospects.
Like yourself I also did not have the best GCSE grades so I had to start off at level 2 and in order for me to progress their only request was that I passed with an a or b distinction/merit, I wanted to go to night classes and at least get improved english/maths grades but they suggested I didn't ! as a good grade on the B tech level 2 would be enough even though to do level 3 you need C or above in those subjects so you might be surprised how much this wont effect you. Some places definitely push for this more in school leavers than in adults.
I think if I was looking at uni which i'm not as I've been there and wasn't right for me and glad I worked that out as I couldn't imagine myself doing anything now but working with animals, given my age I would look at access or whatever was the fastest way of doing it.