I would be shocked if they implemented any large scale restrictions, hospitalisations are moving up in London but nothing too horrific yet and London has been at very high case levels for a while now.
Not saying it is the right or wrong decision as I have no idea if the NHS is able to cope with those kind of hospitalisation numbers in all areas of the country.
Knowing who is currently PM, I don't think this will be a particularly difficult decision for him, and indeed there is already some briefing coming out that people shouldn't expect any announcements today.