So, in spite of the chill in temperature, I managed to get the start of some painting done, and got some flags attached.
My flags come from GMB Designs, which I ordered from here. I paid about $5 per flag, plus another $5 for total postage. Overall, I am pretty happy with them! They require a bit of cutting to make them fit properly onto the banner poles; but it is really no extra drama. So I ordered enough flags to cover my whole army (the Guards, the 5th British Brigade and the Hanoverians), but I will do another order, I really think I will use them for my next force (probably frenchies...) as well as when I add more regiments to the army to make sure I can use it as a standard Infantry core, as well as Guards.
So, in short, I highly recommend GMB. They are on the expensive side, but... I am alright paying the little bit extra for quality, especially when flags are such a notable part of the unit!
In case you didn't know the importance of the flag, here is comedian Eddie Izzard explaining why the flags were so important!