I'd recommend gap insurance when taking out a lease. You can almost guarantee that there would be a shortfall between the insurer's valuation and what the lease company is owed so for the sake of £200 (that's what I paid SEAT finance) you get that peace of mind.
As for the OP's questions, I'd recommend ordering your new vehicle at least 4 months before the end of your current lease to avoid having to extend your current lease. I work as a fleet manager and have seen factory lead times at numerous manufacturers quite often go above the standard 12 weeks. If the lease company is any good they'll keep hold of your vehicle until you're ready if it does come in early.
Insurance hasn't been noticeably different.
The only other advice I'd give is make sure your mileage prediction is as accurate as it can be. On a personal lease you generally won't get refunded for any mileage you didn't use up, but you'll be charged if you go over and it adds up quickly.
As for the OP's questions, I'd recommend ordering your new vehicle at least 4 months before the end of your current lease to avoid having to extend your current lease. I work as a fleet manager and have seen factory lead times at numerous manufacturers quite often go above the standard 12 weeks. If the lease company is any good they'll keep hold of your vehicle until you're ready if it does come in early.
Insurance hasn't been noticeably different.
The only other advice I'd give is make sure your mileage prediction is as accurate as it can be. On a personal lease you generally won't get refunded for any mileage you didn't use up, but you'll be charged if you go over and it adds up quickly.