I've always wanted to do a road trip round the Baltics.
Basically, ferry to Calais and turn left, keep going to Poland and then into Lithuania, Latvia and Estonia. If brave enough, nip into Russia, through St Petersburg and nip out again into Finland (if not brave enough ferry from Tallinn to Helsinki), round to Sweden, down to Denmark, on to Germany, turn right and home!
I've been told that there are some amazing beaches on the Baltic coast and there is a Lake District in the north east of Poland, which I have been to, but it was January and minus 20-something!
What we saw through the blizzards was very pretty!
I'd also recommend Hungary (Budapest, Lake Balaton), Romania (Bucharest, Constanta and the Black Sea coast, Cluj Napoca, Brasov, Timosara), Bulgaria (Sofia, Varna) and down into Greece.
Driving around Greece was awesome as you don't see many tourists away from the coast, there are ancient ruins all over and you can almost see and feel the Roman Legions marching across the countryside.
The food is great as well! At the Greek version of the Burger Van, the Kantina there are great kebabs to be had! Yum!!
I've not been, but a friend has been to Slovenia a few times and raves about the place! Also have you considered heading south across the Med to Morocco? Another friend did a 'Banger Rally' a few years ago to Timbuktu, which is probably not so good these days
, but said Morocco was great.
Keep an eye on what happens if we end up in
'No Deal' territory as Junker has said that British people will not be able to bring pets into the EU, so you might be able to take Fido to Blighty but not out again.
Such a nice chap!