The Bank Of England is expected to put interest rates up by a quarter point this week, you can expect that to give the pound a bit of a boost, though not by a huge amount, as the Forex markets have been expecting a rate rise in the UK for a while now.
The likelihood is that the pound will continue to creep up against the dollar, but by how much between now and christmas is debatable. The trend right now is for UK rates to go up, but if the expected hike does come this week, it 's unlikely the BofE will impose another rise until after the christmas shopping season has come and gone, and they have had a chance to see what effect the (expected) rise this week has on consumer spending. I'd think we wouldn't see another rise till perhaps Febraury or March at the very earliest, always assuming we dont get a huge rise in spending over Chrimbo.
Personally I'm slightly surprised the pound has risen quite as high as it has already, so I think it's upside is diminishing, 1.75 seems a reasonable forecast, but as I pointed out once before whan someone else asked about the possible direction of the pound, if you're happy with the rate as is, and aren't changing up a massive amonut of sterling (for every one cent rise in the £/$ rate, you only get one more dollar for every £100 exchanged), buy at least some of your $'s now, and if it goes up further, thats a bonus !
That also covers you in the (unlilely) eventuality that the UK rates dont go up as expected this week, and thatthe Fed Reserve in the US surprises markets and hikes their rate - they've had some extremely good, unexpectedly high growth rate figures in the last few weeks. Again, a hike is very unlikely, but stranger things have happened...
In short, I think you're ok to wait a while, but if you are concerned, get, say, a third or half your cash now, and the rest nearer your deparure date - you wont lose much, but could gain a bit more.
Hope this helps.
