this can depend on the hunt, for example, drag packs don't have autumn hunting, so their open season can start before the foxhounds.
generally autumn hunting starts about september with open season starting in october/november. the season usually finishes in march.
winkfieldsnowball are you loaning your horse to some one for hunting or leasing him to them , as my horse is being leased to a family who hunt while my leg mends !
we start hunting late oct/early nov, and our last day is 29th march this year - we finish late as we're hunting over moorland late in the season. our last day is brilliant - we have a champagne breakfast, followed by a gallop (about 2 miles with optional jumps) then a meet and a fab days hunting, then we all retire to the marquee for strawberries and more champagne... its the best day ever and it never seems to rain either!