In the Uk you can't divorce on a 'no fault' basis until you have been separated for 2 years. If he or his wife want a divorce before 2 years then then one of them will have to divorce the other for unreasonable behaviour or adultery. If its an amicable divorce then they may not see the point in doing that.
Me and my exdh had an amicable divorce (grew apart) so we didn't divorce for 2 years after we had separated. We actually lived together for 6 months after we had made the decision to split to give the dc time to adjust and to buy our own properties. I classed myself as seperated from the moment we decided to split, although obviously didn't date anyone whilst we were still living together!
Once I had moved out I had to adjust to being without him and new routines with the kids etc. It takes / took a long time before I could even imagine getting involved with someone. It takes time to get over a relationship of that length - especially when it starts at such a formative part of your life.
i started dating by now dh after I had been separated about 2 years. I was still married to exdh, although we started the divorce proceedings after 2 years as we both just wanted to get it done. No aggro, we were in a good place and quite friendly about it.
Even though I was still technically married, I had been living apart for 18 months.
You will soon clock if he is genuinely separated IMO - he won't let you come to his place, meet his friends or family and be secretive with his social media.
Even if he is genuinely seperated I would be mindful of him moving on so quick. Having said that, I do think it takes women longer to detach after a divorce.