degree query

so i have applied for a course of Beng, Aerospace engineering in Bristol, rather than Meng due to fees issue for now, can i pursue the final year of Meng as a masters couple of years after i do my Beng course? or i wont have that option later?? because i want to become a chartered eng

You probably will be able to transfer onto the MEng after first or second year (email Bristol to check) if you can sort out the fees issue.
if not you will be able to do a postgraduate masters which will be an MSc rather than an MEng, however BEng + MSc is equivalent to an MEng if both are accredited (and you could also change university for the MSc if you wanted).
to become a chartered engineer you need a masters equivalent education, you can do this through both an MEng, or BEng + MSc, or even through a BEng + further professional development training courses through your career (although going the industry professional development path is tougher as its not easy exactly what professional training programs are deemed “equivalent” and industry training courses are much more expensive then a degree its not unusual for them to cost a couple grand for a one day group session).
but yes if you start a BEng you’ll be fine, you can either figure out fees and transfer onto the MEng or do a one year postgraduate MSc (you may have to do the MSc at another university depending on what is offered but there are plenty of taught masters in aerospace/mechanical engineering & related)

so will I be able to pursue the last year of Meng after a break of lets say 2-3 years? like instead of applying for a Msc apply for Meng last year course if they do? if not is it better to do beng followed by an Msc or just do an Meng? will i miss out on anything