Far more important issue with a December GE:
https://www.thetimes.co.uk/article/december-election-could-bring-curtain-down-on-nativity-plays-bgm55hd3h
A December election would have to be run using two versions of Britain’s register of voters,
posing unique difficulties for the organisers, ministers have been warned.
Returning officers and the Electoral Commission have raised concerns with the Cabinet Office about the logistical problems of a pre-Christmas election,
should <a class="break-all" href="http://go.mumsnet.com/?xs=1&id=470X1554755&url=www.thetimes.co.uk/topic/boris-johnson" target="blank">Boris Johnsonon succeed in calling one.^
These include asking schools to reschedule nativity plays to make way for polling stations,
hiring outside lighting to illuminate the stations at night as well as drawing up contingency plans to deal with bad winter weather.
In particular, they have highlighted
changes to the electoral register that are due to come into effect on December 1
Councils are duty-bound to update their electoral registers annually
....
The Cabinet Office has been told that if Mr Johnson were successful in calling an election next week, local authorities would be left in a bind.
They would have to send out polling cards to voters using the old electoral register
but would have to run the election using the new register, at the start of December.
The law stipulates a minimum 25-day period between an election being called and polling day, with cards being sent out at the start of the process.
This would mean that polling cards would be sent out using the old version of the electoral register
while election staff working in polling stations would be checking names off against the new version of the list**
< what could go wrong ... >