There is a new month-long lockdown in England that is expected to be announced shortly.
Outbound international travel will be banned.
Will inbound international travel be affected during the duration of this new lockdown?
No it won't. As per this analysis by the Independent:
There is no impact on inbound travel, though of course existing quarantine rules apply.
Assuming you are returning to the UK during lockdown, there is a good chance that your flight will operate as normal.
However, the ban on international travel means that airlines and holiday companies are likely to cut back services to reduced their losses.