I don’t think any of us can answer this question for you, it should be down to your personal preferences and circumstances.
Foundation vs Law LLB
Between these two courses, I would ask yourself if you feel ready to head straight into a law degree, as you mention your English could still use some work. I personally don’t have any experience of foundation programmes, despite speaking English as a second language (albeit at a native capacity), so I can’t comment on whether they are challenging or if universities like them. If you think you might struggle to perform well by heading straight into your LLB, this might be a good option, however, I would also bear in mind that this is more costly. I don’t believe it would disadvantage or advantage you for jobs (apart from assisting you in getting better grades in your LLB) but it is an extra year of study.
QMUL vs Exeter
Living in London is an entirely different experience to attending university in smaller cities, again this comes down to what you will thrive in. I find that London is more competitive, pushing me to perform better. Having attended open days at both, they all have great facilities and libraries. I preferred QMUL’s teaching standards to Exeters, but I would recommend looking at the structure of the courses, the optional modules available, and costs of living in either city when making your decision.
At the end of the day, there is no right answer! It is all down to where you will perform best – grades matter a LOT. So, will foundation help you perform better? Which university suits you more? That is what you should be thinking about, not just reputation. I hope this helps.