I would only do a full roast dinner if you are confident that you can get it on the table with all the timing right. I struggle with that!
I think that I might do a chicken and mushroom casserole, with dumplings if you want to be very traditional!
You don't say exactly when they are coming over, but if soon, I wouldn't do Eton Mess with straberries, but have had it done with poached spiced plums. Apple & blackberry crumble is easy & traditional.
You said 'dinner' but I would be tempted to give them a proper 'high tea' which is very traditional, and not found in other parts of the world. A proper piece of ham to carve, maybe smoked salmon (or pork pie!), your cheeseboard would shine (instead of being at the end of a big meal). Some lovely cake, that would be delicious! Also easy to prepare in advance.