I'm sure you'll crack it mate.Great list of achievements there @Reece. I hope to crack the 100 miles next year.
I found doing it as a Sportive good as there is the feed stations and recovery wagon if needed. Although I've done a few near on 100mile ride with a friend and they were just as good and better in the sense you can choose the route.
I'm looking forward to the tour of wessex in May, but main concern is eating enough and riding 112 miles a day for 3 days and 26000ft of climbing in total. Mainly what to eat in the evening while camping.