@Joeldram I've actually just bought one of the SIM cards @suffolkboy mentioned on eBay - £33 for 24gb over 2 years is pretty decent! Plan to use phones as WiFi hotspots over long journeys to make sure it lasts but means we won't have to worry about plugging in and getting things working on short trips.
Anyway, hopefully this is useful.
https://www.ebay.co.uk/itm/Three-Pay....m46890.l49286