Hi,
Sorry to hear that things aren't going well for you and that you've been having a difficult time.
You have mentioned your interest in history and the fact that you would like to do that but you're concerned about the job prospects. However, getting a job doesn't really have that much to do with what you study at university as it's about all of the other things that you do with your time whilst you're there. If you're really not liking your course then it's unlikely that you will take full advantage of the options available to you at uni and this is what will get you a job in the long term, not the name of the subject on your certificate. Secondly, if you really don't like your course it is unlikely that you will do as well as in something that you actually like meaning what could be a first class degree in one subject may turn into a 2:i or lower in another subject. In the long term the degree classification really won't mean much but it could do for getting your first job as so many graduate schemes require X degree classification as a way of filtering out applicants.
In terms of the jobs that people go onto do after a certain degree, it's generally self selective due to the nature of the programme. People who enjoy history are more likely to take a job in a museum than someone who studied economics simply down to personal interest. Likewise, someone who studied economics is more likely to end up in the financial industry as that's what they're interested in... and consequently, some jobs do pay more than others, so the starting salary of an economics graduate is likely to be higher simply down to self selection as they generally apply for roles that happen to have a higher starting salary than a history graduate. That's not because history graduates are "worth less" - it's simply down to interests and the salary differences across certain sectors. Likewise, even if you do graduate with a degree in economics it is unlikely that you will then be jumping to join the finance industry if you're not enjoying it at only one term in. Therefore it's likely that due to your interests you will be chasing after similar jobs to a history graduate anyway - and it's not to say that a history graduate couldn't go off into an economics related role anyway as for the vast majority of graduate entry roles you just need a good degree. Have you had any thoughts about what you would like to do after uni? It's okay if not, most people don't know and/or change their mind.
At the moment it sounds like you're in a position where you feel like you can't tell your parents or family how you really feel about your course as you say that they will be disappointed, is that right? What do you think they would be more disappointed about long term - that you carried on with something that you really didn't enjoy just to please them or that you asked for their help in making it right? One of the hardest things to do in life is to tell someone that you made a mistake because it's so much harder to admit this than to carry on pretending that everything is fine. If you're struggling to do that after a couple of months, then you're going to really struggle to keep this going for another two and a half years.
In terms of what to do now it sounds like what you need is time and options. Right now you do not need to make any big decisions like telling your uni that you are definitely not going back unless you really want to do so. I assume you have already paid for your accommodation and are committed to that for the end of the academic year, so you may as well go back to your current uni in January and start making plans to move elsewhere. It sounds like you've done a fair amount of research and have a good idea of where you would like to apply to for your new course. I would advise making an application to these courses and seeing what happens. It will only cost you the price of a UCAS application, and then you will know where you stand. You may get to the end of the year and decide to come back to your economics course in September and that's completely fine - all you'll have lost is just over £20 and had some time to think.
Telling your parents that you have made a new application and have some offers at some other universities to do a course that you want to do shows a lot of positive aspects - your plan is not to "live at home and sponge off your parents with no job" and if you go to them with a clear plan they will know that this is the case. How does that sound to you? Your granddad will be proud of you as you are at uni and it's clear from your post that you want to continue to be at uni, just at a different one to where you are now... that's all it is and their opinions of you will not change.
In terms of references, you can either ask someone from your school or someone from your uni now if you don't want to share your application plan with school. When are you going back to uni in January? Is there a tutor that you could contact before then?
Good luck