Very few employers take on students for 6-8 weeks unless they're proper corporate placements/internships/work experiences, etc. It takes several weeks to train you and months for you to become proficient, by which time you're leaving. There's no point in hiring someone for two months when they could hire an employee who they have a chance of retaining.
The handful of employers that don't really mind who you are will be those with very high staff turnover rates, or those with a centralised HR structure which allows for employees to move between stores if they go to uni (e.g. supermarkets, but it's still unusual to be taken on for such a short period by one store before you move to another). By far your best bet is, as someone else mentioned telesale/telemarketing. It's a **** job, which is why people leave after 2 months anyway. Employers expect a high turnover so they'll usually take literally anyone who hasn't worked for them before.
As to knowing which jobs to go for, it's sensible to be realistic; think of jobs which require little/no training, have low enjoyment levels, low pay and don't require any particular skills, abilities or experience (your example of refuse collector isn't great, as they tend to require physical fitness/strength, a strong proven work ethic, teamworking ability, often an LGV license, basic mechanical knowledge, hazardous waste training, health and safety training, etc - despite the lack of qualifications it requires, it's not that straightforward).
Data entry, telesales and basic factory work are your best bets.