You can bring your charger to re-charge you laptop, but make sure it (and any other electronics) you bring on board are charged up when you bring them to the airport. You never know when security might ask to power up your laptop or phone or whatever to prove that it works.

There are no outright bans on electronics flying TO the UK at the moment. But uncharged electronics can cause a problem if security asks you to power it up and you can't. Them asking you to do that doesn't happen often, but you can't rule it out.