I thought first year didn't count for anything? I guess maybe it does at Warwick then.
It's not the end of the world either way. You still have year 2 and 3 to go. You said yourself that you could have put more work in so just take this as a lesson. As for modules such as Probability, not much you can do. Some modules you may find difficult no matter how much work you put in. But if you work hard in everything, one or two bad modules shouldn't have too much of an effect.
On my Maths degree, only 2nd and 3rd year counted. I averaged 59.5% in my 2nd year so I spent the entire of third year being nervous that I'd get a 2.2 overall. But I worked so hard and averaged over 65% in my third year and I got my 2.1.
Seriously, unless you've got no aptitude for numbers (which obviously isn't true as you managed to get into Warwick) then hard work will get you that 2.1 or even a First. I wouldn't worry.