I’ve had a similar issue recently. I own my home - have lived here for about 2 years now. A new tenant moved in next door a few weeks ago - young, single guy whose children sometimes stay at the weekend. On his free weekends, he has friends over and I’ve had to ask them not to park outside my garage. I also spoke to him about it. They’ve not tried it since, so I’m hoping the message has got through. The way I approached it was that now we’re coming out of lockdown, I’m going to have visitors myself and they’ll need the parking space, and that I’m having work done to the house over the next few months and the tradespeople will need the space. I did phone 101 for police advice. I was told that as it’s private land there’s nothing they can do but that I could buy a no parking sign or barrier. I’ve not resorted to the latter but it’s something you might consider if a quiet word doesn’t do the trick.