You'll find it nearly impossible.
Even if you do find short term cover, it's very disproportionately expensive. Typically, six months cover will cost the equivalent of around nine or ten months worth of regular annual cover. Three months cover will cost around 50-60% of the annual rate and two months will typically be about 50% of the annual rate. Once you start asking about a few weeks it becomes proportionately even higher.
The reasons are simple: it costs more to issue a non-standard short-term policy. Instead of being a fairly automatic matter the proposal needs individual attention and manual processing and will also have to be referred to an underwriter for individual attention. The risk to insurers is also far higher, for many unacceptably so; it's a fact that short-term policies are far more likely to produce fraudulent claims.
You may think that you can get around it by getting an annual policy and then cancelling after six weeks to claim a pro-rata refund. But you can't: the insurers will recalculate what they would have charged had you asked for short term cover to start with; they'll also add on a policy amendment fee, and if they would not have covered you at all they will recalculate at a truly eye-watering rate (even by comparison to extremely high annual poicy rates for young drivers) which can cost more than the annual policy fee. In practice, after all the adjustments you'll be lucky to see any significant refund (if any at all).
For the six weeks you need transport for it will actually be cheaper to get taxis everywhere and then benefit from no need to worry about drinking or being too tired or stressed to drive.
Sorry, but reality often bites!