There will likely be lots of comments about this, but perhaps find an agent who can advise and help you plan this, yes they do charge but it takes away a lot of the headaches
This site is run by an agency so maybe get in touch with them now for advice
Despite people saying you can do this yourself, it’s simple, it just removes the stress of you can afford it
My wp expired at the same time II left my job, the employer thought there would be no issue and did not bother to cancel it and told me that
I went to immigration to check and was told that I had to leave immediately, I contacted a visa company who helped me sort the mess out, the mess being the non cancellation of the wp. Apparently the company can be fined for not doing this
It’s only a form to be filled in by them and registered