I don't know all the specifics of how things work on your side of the pond, but if they resemble the US at all then where you get your bachelors degree, or I guess a first in your case, is of relatively little importance compared to where (and with whom) you get your PhD. The bachelors degree is important for where you get accepted for your PhD, but if you are planning to get your PhD, then your PhD school and adviser will be far more important when you start applying for jobs.
Look at it this way: 20 years from now, when people ask you where you went to school, or where you got your degree, you'll tell them your PhD school. When people introduce you when you give lectures of your own, they'll mention your bachelors institution, but will focus on your PhD school and your work there.
So my advice to you is not to worry. Focus on learning a good, solid foundation in chemistry. Get as much lab experience as you can. Grab one of those big names you were talking about and get on a first name basis with them - especially if you can work in their lab (they'll write you better letters of recommendation for your PhD school of choice). And focus on getting in to the best PhD school you can. In my opinion, that will set you up better for your job prospects after school than your bachelors institution will.