When will ppl from the uk be able to go on holiday abroad?

Despite some holidays being advertised for August/September, this is the information advised at the moment:

The current advice from the government is to avoid all non-essential travel indefinitely, with no date put forward on when domestic or overseas trips can resume.Any further information on when holidays are to be expected could change at the last minute, with experts and tour operators unable to say for definite when trips will resume - especially if coronavirus cases surge.

If you go abroad this summer you will have to go in isolation when you return.

The police will make regular checks on your address to see you have not gone

out.

There's nothing stopping you doing it now.  It is just ADVISED that you shouldn't, and if the country you want to go to requires self-isolation for 2 weeks after you arrive, it's not going to be much of a holiday.

No one knows at this point.

No, because most countries are not accepting tourists during the pandemic.

Nobody knows. Even if UK becomes safe, your destination might not be.