With poor quality you might need IVF-ISCI. If it was just poor count then IVF. IUI is generally less successful and used for unexplained infertility or mild male infertility. The clinic will speak to you about options
You can’t get IVF on the NHS tho if you naturally conceived your first child
The fertility clinic / specialist will go through it all with you! It depends how low and how poor quality it is, as if it’s borderline low then you will probably be given IUI
This is what happened to my sister, his sperm count was low so they had ivf and it worked for them