From their last day of hunting, after they're normal clean up routine, from the next morning they won't get a brush on them so the grease can get back into their coat, their hard feed will be halved straight away and gradually reduced over a couple of weeks, their hay/haylage will be increased; their shoes will be off, feet trimmed and checked, teeth too if needed. They will immediately be turned out during the day suitably wrapped up but still in at night, their rugs will be gradually replaced with lighter ones. By the end of a month you should be able to leave rugs off, at least during the day providing the weather is mild/dry enough. If you still feel cold yourself then they will too, remember they've been mollycoddled all winter, you can't just take their thermals off and chuck them out; you need to be as careful roughing off as you are when bringing back in. Around here, we start autumn hunting late July so horses will need to be back and started a fortnight before (obviously hunt horses are different, they usually only use cobs for AH and the true hunters start work from the fields in mid August.)
Hope that's helped!
Mine get a couple of weeks of lighter work, 2 weeks on very little work, then they get brought back up to speed for eventing! i just try to give them a little break to regain a little condition where necessary and to have a mental check before we go off again.