Shall I risk a Section 8

Possession - Section 8 and Section 21

1) Damage/destruction of furniture
2) Other people allowed to live in the house from time to time(including very young child) despite numerous warnings to tenant
3) Keeping 2 large dogs in house despite 'no pets' rule in contract
4) Possible illegal dog breeding (dog keeps 'accidentally' getting pregnant and tenant admits to selling puppies)
5) Unreported broken window/attempted break-in (I only found out be accident that her ex-husband had tried to break in)
6) Refusal to allow me to enter house to do safety checks (including gas check). Constantly agrees time/date for me to come round and then cancels at last minute. On the most recent occasion she didn't even bother to cancel. I made a long journey to the house (she was definitely at home) but she refused to answer the door despite knocking for over an hour.
7) She is one month in arrears with her rent. She has also been in arrears in the past, but she did clear the past arrears.

After all this I now just want to get her out as quick as possible and get the house sorted out and possibly sold. Whenever I take advice I am told to issue a Section 21 because of the certainty... but I can't afford to wait so long to get her out. As soon as I have issued the notice, she will stop paying rent altogether - and I just can't afford this to be strung out for ages with no rent.

The question... should I risk getting her out quicker on a section 8. And if yes, what grounds should I use?

Also, can I issue a section 8 and a section 21 together?

And, if I issue a section 8, do tenants generally just leave voluntarily anyway... or do they tend to string it out as long as possible?