membrane sweep UK

Vicky
So I have had a consultant appointment today, and they won't do an induction even tho I'm in pain with pelvic girdal pain and sciatica I'm house bound and have a 2 year old. 
So iv got a sweep booked for Monday. Then the 7th oct (his due date) il be 40 weeks, I have to go to a day assessment unit at the hospital to see if they will induce me.... 😩 I just want him out I'm in so much pain. 
So my question is ...
what is envolved in a sweep?
What to look out for?
How long after did u go in to labour? 
Thanks ladies