anyone have any advice on whether its worth doing a masters for engineering?
From what I know, if you definitely want to go into engineering you're better off doing the integrated MEng as most big companies prefer that and it'll help you become chartered.
You can do a masters at another institution offering a recognised MSc (and these often require you to have a 2:1) or choose an institution that offers a MEng in the first place.
Do note that institutions may have progression requirements in the MEng course and you may not progress to the 4th year without achieving some threshold grade.