I sold my round last year due to having to relocate due to circumstances within the family.
I knew of a chap that was buying up as much work as he could, so I didn't need to advertise the round as being for sale, which was an advantage for me as I needed a quick and smooth sale. That aside, this is what I did ...
I wrote out an up to date book of all customer addresses and prices, to be handed over to the buyer on receipt of monies. I had emailed him a summary of how many customers and the turnover they generated beforehand, and we agreed a sale price based upon this.
I drew up a contract outlining the sale, outlining the area I was selling, how many customers and the turnover, and which stated that I relinquished all responsibility for said business and that the buyer assumed all responsibility for same. I took a copy for myself and another for the buyer.
We met, signed both copies of the sale document in each other's presence. He then paid me in full, and I handed over the book.
I then wrote to all customers informing them of the changeover and hand delivered each letter. I also gave the buyer a signed letter to introduce him as the new owner of the business.
I sold off the round in three stages, all to the same guy, using this method each time.
Each time the transactions went like clockwork.
Hope this is helpful.
John
PS I am sorry that your injury is forcing your decision to sell.