The Kapitan Khlebnikov visited Halley base in December 2004 as part of one of their Weddell Sea cruises - the first time a cruise ship ever visited our base. See here for details:
We didn't get a chance to visit the ship but they seemed like a very professional operation and all the tourists that came to visit seemed to be having a great time.
I've had a look back at the weather records for October 2005 at our base (75S, 26W, as far south as you are likely to get) - the temperature varied between -3C and -35C with an average of -20C. In terms of wind, we had a few gales in the first third of the month (up to 50 knots) then calmer weather after that. You might get some bad weather but it is unlikely to spoil the whole trip.
As for sea ice, the Khlebnikov shouldn't have any trouble I wouldn't have thought - after leaving here they cut a path straight across the weddell sea to the tip of the pennisula, something our resupply vessel would never manage.
I'd agree with Paul about the sunlight - a good fraction of the time will be light and you'll probably get more spectacular skies than in the summer as the sun will still be setting and rising rather than just going round in circles.
Have a great trip!