If you have internet access how about researching your family tree - a fascinating hobby, made very easy with the Ancestry and other websites which you can access from home.. then there's the odd excursion to records offices too which you could tie in with one of your caravan breaks.
------------- Aug 2017 St Martins Campsite, Scilly
Jul 2017 Trewan Hall, Cornwall
Jun 2017 Higher Kestle Farm, Cornwall
Mar 2017 Pitch Perfect camping Bath
Aug 2016 Brittany/Normandy:-
La Ferme Croas Men (near Morlaix)
Le Ranolien (Ploumanac'h)
Le Bois Courdrais (Cugen)
Chateau de Montfreville (Montfreville)
How about Geocaching? It's like treasure hunting in a big way and it's been going years - take a look at the website below which gives more info.
It's great fun, you will get as much or as little exercise as you choose, and it's something you can do locally from home as well as when you are away in your caravan.
https://www.geocaching.com/play
------------- Aug 2017 St Martins Campsite, Scilly
Jul 2017 Trewan Hall, Cornwall
Jun 2017 Higher Kestle Farm, Cornwall
Mar 2017 Pitch Perfect camping Bath
Aug 2016 Brittany/Normandy:-
La Ferme Croas Men (near Morlaix)
Le Ranolien (Ploumanac'h)
Le Bois Courdrais (Cugen)
Chateau de Montfreville (Montfreville)