It depends, you should call the university that offered you the BEng course and ask them if advancement into the MEng course is possible, if required grades are obtained. If not, you can always finish your BEng there and then do a master's course at a different school, although that may not be funded by student loans. On the other hand, doing an MEng would be a good idea, since it would definately be funded from what I know. University rankings don't really matter too much if you graduate with a 2.1+. Are both of these courses accredited?