It really doesn't feel that way when you're here. It can be a bubble on campus because you don't have to leave the university at all - it has everything. But it doesn't feel isolated, I think that bubbles just makes it feel safer, more unified. The moment you don't want to be in that bubble you don't have to, it's only a little bus drive into the city, and from there you can get to Manchester and other cities very easily. You can go into the peaks, to the shore at Morecambe, visit Preston (if you feel so inclined...) - it's what you make of it. I don't feel it is 'isolated' in a negative way.
As for part-time, if you make the effort and are employable, as with anywhere, you should be able to find a part-time job. There are positions on campus each year - in the bars and in retail on the campus shops, Spar and Central, as well as certain admin/IT positions with LUSU and ISS. My housemates have worked for the shops since first year and largely enjoy it, if you're going to be on campus it's definitely preferable to try and get a spot working here rather than in town. I managed to get a job in a cafe in town very easily last year. It's just about getting out there, having a good CV, and in the campus positions, keeping an eye out and having some relevant experience.